Dolphins

Average Adult Length 7.2–8.9 feet (220–270 cm)

Bottlenose dolphins inhabit warm temperate waters, adapting to a variety of marine and estuarine habitats, including, occasionally, rivers (Ridgway and Harrison, 1999). Bottlenose dolphins usually inhabit waters of less than 9.8 feet (3 meters)

Studies show they can hold their breath up to 10 minutes but some species can hold their breath up to 15 minutes. In our habitat they usually will take a breath every 1-2 minutes. It depends on their activity level and what they are doing. For example, they will most likely take more breaths if racing around and less if they are playing with coral on the ocean floor.

We know that they have rods and cones in their eyes that allow them to see some colors, but unsure of which colors they can see. More research is needed to determine what colors they can see.

On their ventral side under their tail area they have a genital slit. Males have what looks like an exclamation mark and females have what looks like a division sign. Females have the long genital slit in the middle with a mammary slit on each side. Sometimes there are additional false mammary slights. The nipple is located inside the slit closest to the genital slit where the calf will nurse. Males have a genital slit with a smaller anal slit below it.

Top speed averages around 18-20 miles per hour. Speed varies depending on the activity of the dolphin.

Bottlenose dolphins have been shown to engage in “unihemispheric” slow wave sleep (USWS) during which one half of the brain goes into a sleep state, while the other maintains visual and auditory awareness of the environment and allows the animal to resurface for respiration. This ability may help to avoid predators as well as maintain visual contact with cohorts/offspring.

The blowhole on top of their head. There are air sacks around the blowhole that they can manipulate to make a variety of different sounds and it is also where echolocation sound waves are projected from. Echolocation allows them to see through water and since the human body is made mostly of water which allows them to see your bone structure etc.– similar to having x-ray vision.

Sharks are potential predators of coastal bottlenose dolphins, especially tiger, great white, bull and dusky shark.

Coral World dolphins are trained using positive reinforcement. They are encouraged to repeat behaviors they perform naturally.

While we cannot prove scientifically that dolphins enjoy interactive programs, we do know from experience at other facilities that dolphins exhibit excitement by jumping and vocalizing when guests arrive for an interaction.

Just like Coral World’s sea lions, Coral World’s dolphins are never forced to engage in human interaction. The dolphins have access to specialty areas within the sanctuary where they can retreat if they do not wish to interact with humans.

At nearly 2 acres in Water Bay, Coral World’s dolphin sanctuary is one of the largest open ocean sanctuaries in the world. Our facility and interactive programs are regulated by the USDA under the Animal Welfare Act and the Marine Mammal Protection Act. The U.S. regulations are the strictest in the world.

Coral World’s dolphin sanctuary far exceeds U.S.-mandated space requirements for dolphins in human care and our interactive programs are fully compliant. In addition to a large swim area, the facility includes a medical area, a maternity area, and a specialty area where dolphins can retreat if they tire of human interaction.

This state-of-the-art facility and a world class veterinary team ensure exceptional care for the animals.

The dolphins are protected by a mesh barrier in an enclosed area, where they will be safe and will not be able to get out and no one will be able to get in unauthorized.

Anything with a mouth and teeth can bite you. The dog you have had for 10 years at home could one day bite you. The trainers know the dolphins extremely well and can read their behavior. Therefore, the likely hood of them biting you is very unlikely.

Coral World’s dolphins and even their parents were born and raised in human care. They arrived from Dolphinaris Arizona on February 20, 2019, traveling with their marine mammal specialists as well as veterinary specialists who know them personally to ensure their every need was met.

Dolphins in human care have reached ages over 40 years, but on average live 25 years. Recent data provides evidence that dolphins in human care, where they are protected from predators and boat strikes, and where they receive excellent veterinary attention and treatment for parasites, live longer than their wild counterparts.

Taxonomy

The common bottlenose dolphin (Tursiops truncatus truncatus) belongs to the order Cetacea, the subgroup Odontoceti, the family Delphinidae and the genus Tursiops (AMMPA 2017). Within the common bottlenose species, there are two ecotypes that have differing anatomical, physiological, behavioral, ecological and genetic characteristics (AMMPA 2017). These two ecoypes are called offshore and inshore bottlenose dolphins. The information presented in this educational section will pertain to inshore dolphin populations.

Anatomy and Diet

Bottlenose dolphins have streamlined, spindle shaped bodies that help reduce the amount of drag they experience as they swim through the water (Cozzi et al. 2017) . Attached to this body are three types of limbs that have different structural and functional characteristics. The three types of limbs found on the bottlenose dolphin are the pectoral flippers, the fluke or tail fin and the dorsal fin (AMMPA 2017) (Figure 2). Pectoral flippers are modified forelimbs that evolved millions of years ago from a land based ancestor. As a result, pectoral flippers have an internal structure that is similar to terrestrial animals such as a modified shoulder, elbow, wrist and phalanges (AMMPA 2017; Cozzi et al. 2017)(Figure 3). Since these animals live in the ocean, the function of the pectoral flipper is to help the animal swim through the water column (AMMPA 2017). The fluke or tail fin propels the dolphin through the water and is formed from outgrowths of skin and connective tissue (AMMPA 2017). The dorsal fin functions as a rudder, steering the animal through the water and preventing it from rolling over. The dorsal fin can also regulate the internal body temperature of a dolphin. The body of the common bottlenose dolphin is usually a slate gray to charcoal color (AMMPA 2017). Countershading is common amongst bottlenose dolphins and is believed to be a form of camouflage. The size and weight of adult bottlenose dolphins varies by their geographic location with larger individuals in northern latitudes and smaller individuals near the equator. Nevertheless, the average length of bottlenose dolphins in aquarium facilities is 8.5 feet and ranges from 7.2-8.9 feet in wild populations (AMMPA 2017t).

The head of the bottlenose dolphin is characterized by a beak-like snout called a rostrum connected to a large fatty structure called the melon that is used to transmit echolocation signals (AMMPA 2017; Haper 2007) (Figures 2, 3, 4, 5). The rostrum in bottlenose dolphins is longer in shape than it is in other delphinidae. Scientists believe that this elongated rostrum helps the dolphin catch its prey which are usually small species of fish but also cephalopods, crustaceans and small shark and ray species (Cozzi et al. 2017). On each side of their head are two eyes and two small ear opening that are connected to the dolphins ear canal (Figure 2). Bottlenose dolphins breathe through an orifice located on top of their head called a blow hole (Figures 2, 3). The blow hole remains closed when the dolphin is submerged and opens when they reach the surface to breath (Cozzi et al. 2017). The blowhole is connected to a vertical nasal passages that contains a frontal air sac and a distal air sac that is used by dolphins and other toothed whales to create clicking sounds (Cozzi et al. 2017) (Figures 4, 5).

Dolphins have a thick layer of smooth, rubbery skin lined with cutaneous ridges that protects the animal from external stressors, regulates the animals internal body heat, allows for sensory perception and that may decreases the amount of drag they experience while swimming (Ridgway and Carder 1993; Cozzi et al. 2017). The epidermis, or out layer of skin, for adult bottlenose dolphins, lacks sweat glands and hairs. However, in newborn dolphins, hair is present on both sides of their rostrum (Cozzi et al. 2017) (Figure 6). To keep their body surface smooth and reduce drag, bottlenose dolphins shed their epidermis every two hours or 12 times a day (AMMPA 2017). Beneath the epidermis there is a layer of skin called the “dermis” that contains blood vessels, nerves and connective tissue (AMMPA 2017). Dolphins also have a layer of fat called “blubber” that contains collagen and elastic fibers beneath their dermal tissue layer (AMMPA 2017, Cozzi et al. 2017). Blubber provides dolphins with thermal insulation, a location to store metabolic energy, increased buoyancy and protection from predators (AMMPA 2017, Cozzie et al. 2017). Blubber also forms the dorsal fin, fluke blades and caudal keels of dolphins (Cozzi et al. 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017). Fact Sheet: Bottlenose Dolphin. Online Publication:
https://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinFactSheet-FINAL-Web.pdf

2. Cozzi, B., Huggenberger,S., Oelschalager, H. (2017). Anatomy of Dolphins Insights into Body Structure and Function. Elsevier.

3. Harper, C. (2007). Morphology of the melon and its tendinous connections to the facial muscles in Bottlenose Dolphins (Tursiops truncatus). A Thesis submitted to the University of North Carolina Wilmington in partial fulfillment of the requirements for the decree of master of science. University of North Carolina Wilmington.

4. Ridgway, S.G., Carder, D.A. (1993). Features of dolphin skin with potential hydrodynamic importance. Engineering in Medicine and Biology Magazine, IEEE, 12(3): 83-88.

When compared to other non human animals, dolphin cognition is quite sophisticated in many areas (AMMPA 2017). Dolphins are able to learn the concept of “same” by matching objects that they see visually to those that they perceive by echolocation (AMMPA 2017; Herman and Gordon 1974; Pack and Herman 1995; Mercado et al. 2000) are able to remember learned skills for many years and have a working memory (ie. they can retain information from recent events for a few minutes) (Mercado and DeLong 2010). Although much less is known about dolphin long-term memory (Mercado et al. 2000) a study conducted by Bruck (2013) found that dolphins are able to remember signature whistles from former tank mates for up to 20 years.

Dolphins also have a basic understanding of the physical world around them (AMMPA 2017). For example, dolphins are able to distinguish between object size and number (Murayama et al. 2012; Jaakola et al. 2005) and have a fundamental understanding of object permanence (ie. they understand that an object still exists even though it is out of site) (AMMPA 2017; Jaakola et al. 2010). Studies suggest that dolphins also have the ability to understand aspects of their social world (AMMPA 2017). In the wild, dolphins have also been observed cooperating with one another during numerous feeding strategies such as rushing fish into shallow waters or trapping them against a coral reef (AMMPA 2017; Hoese 1971; Gazda et al. 2005). In addition, a study conducted by Reiss and Marino (2001) found that two dolphins were able to use a mirror to identify certain marked parts of their body. This study suggests that dolphins may possess mirror self-recognition, a trait that has only been observed in humans and great apes (Reiss and Marino 2001).

Certain aspects of symbolic cognition have also been observed in dolphins. Bottlenose dolphins use specific whistles called “signature whistles” when referring to other individuals, similar to how humans use names (Janik et al. 2005; Quick and Janik 2012). In addition, dolphins have been shown to understand certain human communicative signals that refer to objects such as pointing and directed gaze (Tschudin et al. 2001) and have a basic understanding of simple syntactic rules (AMMPA 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017).Fact Sheet: Bottlenose Dolphin. Online Publication: http://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinF actSheet-FINAL-Web.pdf.

2. Bruck JN. 2013 Decades long social memory in bottlenose dolphins. Proc R Soc B 280: 20131726. http://dx.doi.org/10.1098/rspb.2013.1726.

3. Gazda, S. K., R.C. Connor, R.K. Edgar, and F. Cox. 2005. A division of labour with role specialization in group-hunting bottlenose dolphins (Tursiops truncatus) off Cedar Key, Florida. Proceedings of the Royal Society of London B 272: 135-140.

4. Herman, L. M., and J.A. Gordon. 1974. Auditory delayed matching in the bottlenose dolphin. Journal of the Experimental Analysis of Behavior, 21: 19-26.

5. Herman, L.M. (2002). Exploring the cognitive world of the bottlenose dolphin. In: The Cognitive Animal, M. Bekoff, C. Allen, and G.M. Burghardt, ed. (Cambridge, Mass.: MIT Press), pp 275–283.

6. Hoese, H. D. 1971. Dolphin feeding out of water in a salt marsh. Journal of Mammalogy, 52: 222-223.

7. Jaakkola, K., W. Fellner, L. Erb, M. Rodriguez, and E. Guarino. 2005. Understanding of the concept of numerically “less” by bottlenose dolphins (Tursiops truncatus). Journal of Comparative Psychology 119: 296-303.

8. Jaakkola, K., E. Guarino, M. Rodriguez, L. Erb, and M. Trone. 2010. What do dolphins (Tursiops truncatus) understand about hidden objects? Animal Cognition 13: 103-120.

9. Janik, V.M., Saylgh, L.S., Wells, R.S. (2005). Signature whistle shape conveys identity information to bottlenose dolphins. PNAS, 103(21): 8293-8297.

10.Mercado, E., III, D.A. Killebrew, A.A. Pack, I.V.B. Macha, and L. M. Herman. 2000. Generalization of ‘same-different’ classification abilities in bottlenosed dolphins. Behavioural Processes 50: 79-94.

11.Mercado, E., DeLong, C.M. (2010). Dolphin cognition: representations and processes in memory and perception. International Journal of Comparative Psychology. 23:344-378.

12.Murayama, T., A. Usui, E. Takeda, K. Kato, and K. Maejima. (2012). Relative size discrimination and perception of the Ebbinghaus illusion in a bottlenose dolphin (Tursiops truncatus). Aquatic Mammals 38: 333-342.

13.Pack, A. A., and L.M. Herman. 1995. Sensory integration in the bottlenose dolphin: Immediate recognition of complex shapes across the sense of echolocation and vision. Journal of the Acoustical Society of America 98: 722-733.

14.Quick, N.J., Janik, V.M. (2012). Bottlenose dolphins exchange signature whistles when meeting at sea. Proc. R. Soc. B, 279: 2539-2545.

15.Reiss, D., and Marino, L. (2001). Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proc. Natl. Acad. Sci. USA 98:5937–5942.

16.Tschudin, A., Dunbar, R.I.M., Call, J., Harris, G., van der Elst, C. (2001). Brief communications: comprehension of signs by dolphins (Tursiops truncatus). Journal of Comparative Psychology, 115(1): 100-105.

Dolphin Hearing and Echolocation

Almost all aspects of a dolphins life history including communication, reproduction, development and the use of echolocation to forage and navigate their environment are dependent upon their ability to produce and hear sounds underwater (AMMPA 2017). Within the first few months of life, bottlenose dolphins will produce a signature whistle that remains with them for the majority of their life (Quick and Janik 2012). Scientists have observed dolphins using these signature whistles to cooperate with on another, address and identify other dolphin individuals and to help bring mother and baby dolphins together (AMMPA 2017).

Since dolphins can live in murky waters, they have developed a biological, sonar ability called echolocation (AMMPA 2017). During echolocation, dolphins produce high frequency clicks by pushing air through a structure called phonic lips, located in their nasal passage (Cranford and Amundin 2004; Marriott et al. 2013). These clicks are sent out into the environment through a fatty organ on the top of their head called the “melon”(Cranford and Amundin 2004; Marriott et al. 2013). The high-frequency clicks produced by the dolphin, bounce off of objects and return back to the dolphin as an echo. “Echos” travel from the dolphins lower jaw to the middle and inner ear and eventually into the hearing center of the brain (Cranford and Amundin 2004; Mooney et al. 2012; Marriott et al. 2013) (Figures 4,5). Echolocation enables dolphins to perceive an object’s size, structure, composition, speed and direction of movement from over 230 feet away (AMMPA 2017).

Dolphin Eyesight

Species in the family Delphinidae (dolphins and porpoises) appear to better vision than all other whale species (Tinker 1988). Although dolphins primarily use monocular vision to process visual stimuli (ie.they see primarily with one eye at a time), the structure of their eye suggests that they have the ability to use binocular vision which may give them a sense of depth perception (Tinker 1988; AMMPA 2017). Dolphins may use one eye over the other when investigating known and unknown objects. For example, results from a study conducted by Blois-Heulin et al. (2012) found that dolphins primarily used their right eyes to investigate unknown objects and their left eye to investigate known objects. This study suggests that like humans and other animals, dolphins may use both sides of their brain process different visual stimuli (Blois-Heulin et al. 2012). Scientists do not know for sure if dolphins can see different colors. Based on the absence of certain cones in their eyes, dolphins are not able to see colors in the green spectrum and many believe that they are not able to see colors at all (AMMPA 2017). Some behavioral studies do suggest that dolphins have the ability to see different colors, however, the results from these studies are inconclusive since dolphins may be responding to brightness instead of color (AMMPA 2017). Dolphins have a double split pupil that gives them the ability to see above and below the water (AMMPA 2017).

Dolphin Smell

Unlike other land animals, dolphins cannot smell since they do not have an olfactory system in their brain (Marriott et al. 2013; AMMPA 2017).

Dolphin Taste

Most scientists agree that dolphins may have some kind of sensory ability within their mouth. Results from behavioral studies suggest that dolphins may be able to detect sweet, bitter, sour and salty tastes. However, it is still not known how dolphins use this ability to detect these four tastes and many scientists are unsure if dolphins have taste buds at all (AMMPA 2017).

Dolphin Touch

Dolphin skin is extremely sensitive to external stimuli such as vibrations which suggests that they have an acute sense of touch. Certain parts of their body such as their eyes, blowhole, rostrum and genital areas have high concentrations of nerve endings which suggest that these areas are more sensitive to touch than other parts of their body (AMMPA 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017).Fact Sheet: Bottlenose Dolphin. Online Publication: http://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinF actSheet-FINAL-Web.pdf.

2. Blois-Heulin, C., Crével, M., Böye, M., & Lemasson, A. (2012). Visual laterality in dolphins: importance of the familiarity of stimuli. BMC Neuroscience, 13, 9. http://doi.org/10.1186/1471-2202-13-9.

3. Cranford, T.W., Amundin, M. (2004). Biosonar Pulse Production in Odontocetes: The State of Our Knowledge. In J.A. Thomas, C.F. Moss, M. Vater (Eds), Echolocation in Bats and Dolphins (pp. 27-35). Chicago, Illinois: The University of Chicago Press.

4. Marriott, S., Cowan, E., Cohen, J., Hallock, R.M. (2013). Somatosensation, echolocation, and underwater sniffing: adaptations allow mammals without traditional olfactory capabilities to forage for food underwater. Zoological Sciences, 30: 69-75.

5. Mooney, T.A., Yamato, M., Branstetter, B.K. (2012). Hearing in Cetaceans: from natural history to experimental biology. Advances in Marine Biology, 63: 197-246.

6. Quick, N.J., Janik, V.M. (2012). Bottlenose dolphins exchange signature whistles when meeting at sea. Proc. R. Soc. B, 279: 2539-2545.

7. Ridgwar, S.H., Au, W.W.L. (2009). Hearing and echolocation in dolphins. Encyclopedia of Neuroscience, 4: 1031-1039.

8. Tinker, S.W. (1988). Whales of the World. Leiden, New York, Honolulu, Hawaii: Leiden.

Dolphin Swimming

Because of their streamlined and spindle shaped bodies, Dolphins are some of the world’s best swimmers (Williams and Worthy 2002; AMMPA 2017). On average, bottlenose dolphins can swim at speeds ranging from 4.6 to 5.6 feet per second (ie. 3.34 to 3.82 miles per hour). However, on a regular basis, dolphins can swim at speeds up to 10.2 feet per second or 6.9 miles per hour and in extreme cases, dolphins have been known to swim as fast as 18.2 miles per hour (AMMPA 2017). In addition, the maximum vertical speed observed in a bottlenose dolphin prior to a vertical leap, was recorded at 25.09 miles per hour (AMMPA 2017).

Dolphin Diving

Like other whale species, during a dive, dolphins must regulate and conserve the amount of oxygen that they have in their bodies (Panneton 2013; AMMPA 2017). To conserve oxygen during a dive, dolphins reduce their heart rate and constrict their vascular vessels, reducing the amount of oxygen that reaches their visceral organs, skin and muscles and concentrating it in more oxygen demanding organs such as the brain (AMMPA 2017). The amount of time spent during a dive has been found to differ substantially by the time of day with shorter dives in the morning and longer dives in the evening (AMMPA 2017). In addition, maximum breath hold has been found to vary between coastal and offshore dolphins with a maximum breath hold of 7 minutes and 15 seconds reported for a coastal dolphin and a maximum breath hold of 14 minutes reported for one offshore dolphin individual in Bermuda (AMMPA 2017). Nevertheless, the average amount of time spent during a dive for coastal dolphins ranges from 20-40 seconds with a mean of 28.5 seconds and the average dive depth is usually less than 9.8 feet (AMMPA 2017).

Dolphin Thermoregulation

Like other mammals, dolphins regulate their internal body temperature by controlling the flow of blood throughout their bodies (AMMPA 2017). When at rest, little heat is built up in their bodies, however, when in motion, heat is dissipated through their flukes and flippers which reduces their internal temperature and protects organs such as the heart, brain, lungs and gonads that are sensitive to high temperatures (AMMPA 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017).Fact Sheet: Bottlenose Dolphin. Online Publication: http://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinF actSheet-FINAL-Web.pdf.

2. McCafferty, D.J., Pandraud, G., Gilles, J., Fabra-Puchol, M., Henry, P-Y. (2018). Animal thermoregulation: a review of insulation, physiology and behavior relevant to temperature control in buildings. Bioinspir. Biomim., 13: 1-16.

3. Panneton, M.W. (2013). The mammalian dive response: an enigmatic reflex to preserve life? Physiology, 28(5): 284-297.

4. Williams, T.M, Worthy, G.A.J. (2002). Anatomy and Physiology: the Challenge of Aquatic Living In A.R. Hoelzel (Ed.), Marine Mammal Biology (pp. 73-97). Blackwell Science Ltd, Malden, MA: Blackwell Science Ltd.

Other Resources

1. Costa, D.P. (2007). Diving physiology of marine vertebrates In Encyclopedia of Life Sciences (pp.1-7). John Wiley & Sons, Ltd.

2. Meagher, E.M., McLellan, W.A., Westgate, A.J., Wells, R.S., Frierson, D., Pabst, D.A. (2002). The relationship between heat flow and vasculature in the dorsal fin of wild bottlenose dolphins Tursiops truncatus. The Journal of Experimental Biology, 205: 3475-3486.

3. Williams, T.M., Noren, D., Berry, P., Estes, J.A., Allison, C., Kirtland, J. (1999). The diving physiology of bottlenose dolphins (Tursiops truncatus). The Journal of Experimental Biology, 202: 2763-2769.

Social Organization

Bottlenose dolphins have a complex social organization structure that varies between dolphin groups in human care and dolphin groups that are not in human care (Shane et al. 1986).

Group Size

Bottlenose dolphins are usually found in groups of 2 to 15 animals but group size can vary significantly, ranging from one dolphin individual to a group of 100 dolphins. Factors such as habitat type and dolphin activity patterns, including foraging techniques, have been suggested as the main drivers influencing group size (Shane et al. 1986). For example, shallow, nearshore habitats such as coral reefs and seagrass beds usually have a constant supply of food. Therefore, dolphin group size does not influence the probability of locating and catching prey. In addition, the bathymetry of shallow, nearshore habitats may protect dolphins from their main predators (Shane et al. 1986). Conversely, food is much less abundant in the open ocean and dolphins in these habitats usually obtain their food from large schools of fish. By working together as a large group, dolphins are able to catch more fish than they would in smaller groups (Shane et al. 1986). Various studies have found that dolphin group size increases with depth and habitat openness (Shane et al. 1986). For example, Wells (1978) found that bottlenose dolphin groups were significantly larger in offshore waters located off of the Gulf of Mexico when compared to dolphin groups in shallow waters near Sarasota, Florida. Leatherwood and Platter (1975) also found dolphin groups to be larger in open waters off of the northern Gulf of Mexico than in shallow marshlands and Wursig (1978) found that average group size was smaller in near shore waters than they were in offshore waters (14 dolphins per group versus 20 dolphins per group).

Social Structure and Behavior: Dolphins in Human Care

Dolphin groups in human care are usually structured into a hierarchy with the largest, adult male being dominant over all other individuals (Shane et al. 1986). Dominant male dolphins display their superiority through aggressive behaviors such as jaw claps, biting, ramming and tailslaps against subordinate dolphins (Shane et al. 1986). These aggressive behaviors are frequently observed in dominant male dolphins when they are in contact with subadult male dolphins especially when subadult males attempt to mate with females (Shane et al. 1986). To avoid these aggressive behaviors, subadult male dolphins have been shown to form groups with one another (Shane et al. 1986). For most of the year, dominant male dolphins usually do not swim with females, however, during courtship, dominant male dolphins may form bonds with adult females that can last anywhere from a few days to a few weeks (Shane et al. 1986). Courtship and mating occurs during the late winter and spring and is characterized by behaviors such as rubbing, mouthing, nuzzling, S-curve posturing, jaw-clapping, head budding and yelping (Shane et al. 1986). The gestation period for bottlenose dolphins is approximately 12 months and during this period, pregnant females spend most of their time alone or with another female dolphin referred to as the “auntie” dolphin (Shane et al. 1986). The bond between pregnant dolphins and “aunty” dolphins can continue for months after a calf is born (Shane et al. 1986). During labor, a pregnant female is usually surrounded by other excited female dolphins (Shane et al. 1986).

Social Structure and Behavior: Dolphins in their Natural Habitat

In the wild, bottlenose dolphin group composition is more dynamic and fluid than it is in human care and can change dramatically several times per day (Shane et al. 1986; Lusseau et al. 2003). These constantly changing groups are called fission-fusion societies and have been observed in dolphin communities throughout the world (Lusseau et al. 2003). Studies conducted by Wursig and Wursig (1977, 1979), Wells (1978), Shane (1980), Wells et al. (1980), Irvine et al. (1981) and Wells et al. (1987) found that bottlenose dolphin group composition changed often but certain group associations were more permanent or were repeated more frequently than others. Wells et al. (1980) and Wells et al. (1987) found that groups were formed based on the age and sex of individuals, familial relationships and reproductive condition in dolphin communities off of Sarasota and the west coast of Florida. Within these populations, adult males, females and subadult males and females formed their own segregated, grouping systems. More often than not, small bands of adult males were observed moving between various adult female groups within one portion of the dolphin community and larger groups of subadult male dolphins would inhabit another location (Shane et al. 1986). Although their ranges overlapped in some areas, adult and subadult males were rarely seen together. Occasionally, subadult males were observed moving into female groups that lacked the presence of adult male dolphins (Shane et al. 1986). Adult female groups were further divided into subgroups based off of their reproductive condition (Wells et al. 1987). Female subgroups were composed of females ready to mate (receptive females), pregnant females and females with their calves (Wells et al. 1987). Groups composed of mother dolphins and their calves called “natal groups” were also observed and were further divided into subgroups based off of the calf’s age (Wells et al. 1987). Scientists believe that these different social grouping patterns may be influenced by environmental factors such as predation, food resources and specifically for male dolphins, access to a mate (Lusseau et al. 2003). Dolphins engage in different foraging methods that are influenced by habitat type, prey type and prey accessibility (AMMPA 2017). Bottlenose dolphin foraging strategies include the use of mud plumes, ring feeding, fish herding, kerplunking, crater feeding, beach feeding, sponge feeding and cooperative net fishing (AMMPA 2017). Calves learn these foraging strategies by observing their mothers (AMMPA 2017). Bottlenose dolphins also engage in unihemispheric slow wave sleep (USWS) which is when one part of the brain engages in a sleep state while the other part is aware (AMMPA 2017). During USWS, bottlenose dolphins have one eye closed and the other open (AMMPA 2017).

Although bottlenose dolphin behavior varies substantially between different locations and habitats, a few general observations have been made. (1) observations suggest that dolphins may be active during parts of the day and night, (2) feeding is most commonly observed during the early morning and late afternoon, (3) feeding duration increases during the fall and winter months in waters off of Texas, (4) feeding strategies vary by habitat type and the availability of food resources and (5) social behaviors such as mating and play, are substantial components of the dolphin’s daily activities (Wells et al. 1987)

Bottlenose Dolphin Reproduction and Maternal Care

The average of sexual maturity for bottlenose dolphin wild populations varies by an individual’s sex and geographical location. In their natural habitats, females reach sexual maturity anywhere from 5 to 13 years of age and males reach sexual maturity between 8 and 13 years of age (AMMPA 2017). Females and males under human care reach sexual maturity between 7 to 10 years of age and 7 to 12 years of age respectively (AMMPA 2017). Ovulation usually occurs 2 to 7 times a year and can last as long as 30 days per cycle. Gestation takes approximately 12 months and the birthing season reaches its peak during the spring, early summer and early fall (AMMPA 2017). When born, calves are approximately 111 to 116.3 centimeters long and nurse for approximately 18 to 24 months (AMMPA 2017). During this first year, calves usually start eating fish while continuing to nurse and begin to understand and experience social interactions and behaviors (AMMPA 2017). These newly learned social interactions and behaviors vary between female and male calves. For example, within their first year, females usually learn specific foraging strategies taught to them by their mothers and males usually begin to develop specific social bonds (AMMPA 2017). In their natural habitat, mother dolphins and their calves usually stay together for an average of 3 to 6 years although in one rare case, an individual calf was observed with his mother for approximately 11 years (AMMPA 2017). Nevertheless, calves usually separate from their mothers after the birth of another calf (AMMPA 2017). Female dolphins do not go through menopause and are able to birth and rear calves up to 48 years of age (AMMPA 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017).Fact Sheet: Bottlenose Dolphin. Online Publication: http://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinF actSheet-FINAL-Web.pdf.

2. Irvine, A.B., Scott, M.D., Wells, R.S., Kaufman, J.H. (1981). Movements and activities of the Atlantic bottlenose dolphin, Tursiops truncatus, near Sarasota, Florida. Fishery Bulletin (U.S.), 79: 671-688.

3. Leatherwood, J.S., Platter, M.F. (1975). Aerial assessment of bottlenosed dolphins off Alabama, Mississippi and Louisiana. In D.K. Odell, D.B. Siniff, G.H. Waring (eds) Tursiops truncatus assessment workshop. Final Report to U.S. Marine Mammal Commission, Contract No. MM5AC021 (pp 49-86). Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149.

4. Lusseau, D., Schneider, K., Boisseau, O.J., Haase, P., Slooten, E., Dawson, S.M. (2003). The bottlenose dolphin community of Doubtful Sound features a large proportion of long-lasting associations. Behav Ecol Sociobiol, 54: 396-405.

5. Shane, S.H. (1980). Occurence, movements and distribution of bottlenose dolphins, Tursiops truncatus, in southern Texas. Fishery Bulletin (U.S.), 78: 593-601.

6. Shane,S.H. (1986). Ecology, behavior and social organization of the bottlenose dolphin: a review. Marine Mammal Science, 2(1): 34-63.

7. Wells, R.S. (1978). Home range characteristics and group composition of Atlantic bottlenosed dolphins, Tursiops truncatus, on the west coast of Florida. M.Sc. thesis, University of Florida, Gainesville, FL 32611.

8. Wells, R.S., Irvine, A.B., Scott, M.D. (1980). The social ecology of inshore Odontocetes. In L.M. Herman (eds) Cetacean behavior: mechanisms and functions (pp. 263-317). John Wiley and Sons, New York, NY.

9. Wells, R.S., M.D. Scott, A.B. Irvine. 1987. The Social Structure of Free-Ranging Bottlenose Dolphins.. In: Genoways, H.H.,(ed.), Current Mammalogy. 1: 247-305. New York: Plenum Press.

10.Wursig, B. (1978). Occurrence and group organization of Atlantic bottlenose porpoises (Tursiops truncatus) in an Argentine bay. Biological Bulletin, 154: 348-359.

11.Wursig B, Wursig M (1977) The photographic determination of group size, composition and stability of coastal porpoises (Tursiops truncatus). Science 198:755–756.

12. Würsig, B., M. Würsig. (1979). Behavior and Ecology of Bottlenose Porpoises, Tursiops truncatus in the South Atlantic. Fishery Bulletin 77(2): 399-412.

Bottlenose Dolphin Life-span and Survival Rates

Adult and subadult bottlenose dolphins in human care, have an annual survival rate of 0.97 (AMMPA 2017). This means that 97% of all dolphins in captivity are expected to survive to the next year. Based off of this survival rate, the average lifespan of a bottlenose dolphin in human care is 22.8 years old (AMMPA 2017). Survival rates for adult and subadult bottlenose dolphins in their natural habitat vary from 0.902 to 0.961 and average lifespans range from 8.3 to 17.4 years (AMMPA 2017). In human care, calves have a 78 to 86.3% chance of surviving their first year and a 76 to 77.5% chance of survival in their natural habitats (AMMPA 2017).

Bottlenose Dolphin Predators

Large species of sharks such as tiger, great white, bull and dusky sharks are considered to be the main predators of bottlenose dolphins throughout the world and approximately 31% of all dolphins in Sarasota Bay, Florida, display scars from shark attacks (AMMPA 2017).

Bottlenose Dolphin Conservation

Although bottlenose dolphins are not currently listed as threatened or endangered under the US Endangered Species Act or the International Union for the Conservation of Nature (IUCN) list, human induced impacts that negatively impact bottlenose dolphin populations, are increasing around the world (AMMPA 2017). Human induced impacts such as increased habitat loss through development, exposure to chemical pollutants such as pesticides, herbicides and fire retardants, oil, gas and plastic pollution, physical damage and mortality from vessel strikes, entanglement and mortality from fishing debris, and changes in behavior from direct human interactions (AMMPA 2017). Multiple studies suggest that chemical pollutants such as pesticides, herbicides and fire retardants may increase the susceptibility of dolphins to certain diseases and reproductive failure (Cockcroft et al. 1989; Kuehl et al.1991; Lahvis et al. 1995; Schwacke et al. 2002; Wells et al. 2005; Hall et al. 2006; Stavros et al. 2011; AMMPA 2017). Plastic pollution ingestion and entanglement, especially from fishing nets, have caused high levels of injury and mortality in bottlenose dolphins populations around the world. For example, long term studies conducted in Sarasota, Florida, found that 2% of all dolphins were killed each year from ingesting and or becoming entangled in fishing gear (Wells et al. 1998; Powell and Wells 2011; AMMPA 2017). Activities from boating can have a negative impact on bottlenose dolphin distribution, behavior and ability to communicate with each other (AMMPA 2017). In addition, collisions from vessels can cause significant injury and mortality in bottlenose dolphins (AMMPA 2017). Increased exposure to humans can increase the vulnerability of wild dolphins to vessel strikes, fishing gear and plastic ingestion and entanglement, and physical harm from humans (AMMPA 2017). Many scientists believe that these factors will have a substantial impact on coastal dolphin populations in the near future (AMMPA 2017).

Citations

1. Alliance of Marine Mammal Parks and Aquariums (AMMPA).(2017).Fact Sheet: Bottlenose Dolphin. Online Publication: http://www.ammpa.org/sites/default/files/files/animalfactsheets/AMMPA-DolphinF actSheet-FINAL-Web.pdf.

2. Cockcroft, V.G., A.C. Dekock, D.A. Lord, G.J.B. Ross. 1989. Organochlorines in Bottlenose Dolphins, Tursiops truncatus, from the East Coast of South Africa. South African Journal of Marine Science 8: 207-217.

3. Hall, A.J., B.J. McConnell, T.K. Rowles, A. Aguilar, A. Borrell, L. Schwacke, P.J.H. Reijnders, and R.S. Wells. 2006. An individual based model framework to assess the population consequences of polychlorinated biphenyl exposure in bottlenose dolphins. Environmental Health Perspectives. 114 (suppl.1): 60-64.

4. Kuehl, D.W., R. Haebler, C. Potter. 1991. Chemical Residues in Dolphins from the U.S. Atlantic Coast Including Atlantic Bottlenose Obtained during the 1987-88 Mass Mortality. Chemosphere 22(11):1071-1084.

5. Lahvis, G.P., R.S. Wells, D.W. Kuehl, J.L. Stewart, H.L. Rhinehart, and C.S. Via. 1995. Decreased Lymphocyte Responses in Free-Ranging Bottlenose Dolphins (Tursiops truncatus) are Associated with Increased Concentrations of PCBs and DDT in Peripheral Blood. Environmental Health Perspectives, 103(4): 67-72.

6. Powell, J.R. and R.S. Wells. 2011. Recreational fishing depredation and associated behaviors involving Atlantic bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida. Marine Mammal Science 27(1):111-129.

7. Schwacke, L.H., E.O. Voit, L.J. Hansen, R.S. Wells, G.B. Mitchum, A.A. Hohn, and P.A. Fair. 2002. Probabilistic risk assessment of reproductive effects of polychlorinated biphenyls on bottlenose dolphins (Tursiops truncatus) from the southeast United States coast. Environmental Toxicology and Chemistry 21(12): 2752-2764.

8. Stavros, H.W., Stolen, M., Durden, W.N., McFee, W., Bossart, G.D., Fair, P.A. (2011). Correlations and toxicological inference of trace elements in tissues from stranded and free-ranging bottlenose dolphins (Tursiops truncatus). Chemosphere Environmental Toxicology and Risk Assessment, 82(11): 1649-1661.

9. Wells, R.S., S. Hofmann and T.L. Moors. 1998. Entanglement and mortality of bottlenose dolphins (Tursiops truncatus) in recreational fishing gear in Florida. Fishery Bulletin 96(3): 647-650.

10.Wells, R.S., V. Tornero, A. Borrell, A. Aguilar, T.K. Rowles, H.L. Rhinehart, S. Hofmann, W.M. Jarman, A.A. Hohn, and J.C. Sweeney. 2005. Integrating life history and reproductive success data to examine potential relationships with organochlorine compounds for bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida. Science of the Total Environment 349: 106-119.

Dolphin Under Human Care Facilities: Education, Conservation and Research

Bottlenose dolphins have been labeled as charismatic megafauna since they stimulate emotional responses in people. These emotional responses increase environmental awareness in guests and drive conservation related behaviors (Ballantyne et al. 2007). It has been argued that by increasing awareness and appreciation for bottlenose dolphin conservation, other marine organisms may also be protected. Animals that serve this purpose are called umbrella or flagship species and include marine mammals such as dolphins, toothed whales, pinnipeds; marine reptiles such as sea turtles and marine fish such as sharks and rays (Frazier 2005; “CEMEX Conservation Series Book”, 2011a; “CEMEX Conservation Series Book Oceans”, 2011b). Knowledge, attitudes and conservation-related behaviors regarding bottlenose dolphins, have been shown to increase in guests who participated in dolphin educational programs at aquariums and marine parks when compared to those who did not (Miller 2009). In addition, children who visit marine parks and attend dolphin educational programs are more likely to have a closer relationship with the natural environment later in life and are more likely to pursue a career in wildlife conservation and research (Miller 2009).

Studies conducted on dolphins under managed care have provided scientists with an increased understanding of bottlenose dolphin physiology, reproductive behavior, intelligence, social behavior, echolocation and sound production especially since this information is difficult to obtain from dolphins in their natural habitats (AMMPA 2017; Kuczaj 2010). In addition, to truly understand bottlenose dolphin cognition, studies must be conducted in controlled environments such as marine park facilities, where external factors can be controlled (Kuczaj 2010). Previous research analyzed and compiled into a review article by O’Brian and Robeck (2010) found that research conducted on cetacean reproduction in controlled facilities have had a significant positive impact on cetacean conservation efforts. Another study conducted by Houser et al. (2010) found that large amounts of research published by the US Navy Marine Mammal Program have increased our understanding of marine mammal care, conservation and science. This research also benefits the participating dolphins by providing them with enriching behaviors that have been found to increase overall animal welfare (Makecha and Highfill 2018)

References

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