Bottle-nose Dolphin
Facts
Conservation Status: Near Threatened
Location: Tropical oceans and warm waters around the globe
Lifespan: 20 to 40 years
Conservation Status: Near Threatened
Location: Tropical oceans and warm waters around the globe
Lifespan: 20 to 40 years
Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Tursiops
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Tursiops
Description
Length: 2 to 4 m (6.6 to 13 ft)
Weight: 150 to 650 kg (330 to 1400 lb)
Other: They are grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white at the underside. This countershading makes it hard to see, both from above and below, when swimming. Males are on average slightly longer and considerably heavier than females. Their size varies considerably with habitat. Except in the eastern Pacific, dolphins in warmer, shallower waters tend to be smaller than those in cooler pelagic waters.
Length: 2 to 4 m (6.6 to 13 ft)
Weight: 150 to 650 kg (330 to 1400 lb)
Other: They are grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white at the underside. This countershading makes it hard to see, both from above and below, when swimming. Males are on average slightly longer and considerably heavier than females. Their size varies considerably with habitat. Except in the eastern Pacific, dolphins in warmer, shallower waters tend to be smaller than those in cooler pelagic waters.
Behaviour
Bottlenose dolphins communicate through burst pulsed sounds, whistles, and body language. Examples of body language include leaping out of the water, snapping jaws, slapping the tail on the surface and butting heads. Sounds and gestures help keep track of other dolphins in the group, and alert other dolphins to danger and nearby food. Lacking vocal cords, they produce sounds using six air sacs near their blow hole. Each animal has a uniquely-identifying, frequency-modulated narrow-band signature vocalization. The tonal whistle sounds (the most melodious ones) allow dolphins to stay in contact with each other (above all, mothers and offspring), and to coordinate hunting strategies. The burst-pulsed sounds (which are more complex and varied than the whistles) are used "to avoid physical aggression in situations of high excitement", such as when they are competing for the same piece of food, for example. The dolphins emit these strident sounds when in the presence of other individuals moving towards the same prey. The "least dominant" one soon moves away in order to avoid confrontation. The bottlenose dolphin has a single blowhole located on the dorsal surface of the head consisting of a hole and a muscular flap. The flap is closed during muscle relaxation and opens during contraction. Dolphins are voluntary breathers, who must deliberately surface and open their blowholes to get air. They can store almost twice as much oxygen in proportion to their body weight as a human can. The dolphin can store 36 millilitres of oxygen per kilogram of body weight, compared with 20 millilitres per kilogram for humans. This is an adaptation to diving. The bottlenose dolphin typically rises to the surface to breathe through its blowhole two to three times per minute, although it can remain submerged for up to 20 minutes. Dolphins can breathe while "half-asleep". During the sleeping cycle, one brain hemisphere remains active, while the other hemisphere shuts down. The active hemisphere handles surfacing and breathing behavior. The daily sleeping cycle lasts for about 8 hours, in increments of minutes to hours. During the sleeping cycle, they remain near the surface, swimming slowly or "logging", and occasionally closing one eye. Adult males live mostly alone or in groups of two to three, and join pods for short periods of time. Adult female and young dolphins normally live in groups of up to 15 animals.
Bottlenose dolphins communicate through burst pulsed sounds, whistles, and body language. Examples of body language include leaping out of the water, snapping jaws, slapping the tail on the surface and butting heads. Sounds and gestures help keep track of other dolphins in the group, and alert other dolphins to danger and nearby food. Lacking vocal cords, they produce sounds using six air sacs near their blow hole. Each animal has a uniquely-identifying, frequency-modulated narrow-band signature vocalization. The tonal whistle sounds (the most melodious ones) allow dolphins to stay in contact with each other (above all, mothers and offspring), and to coordinate hunting strategies. The burst-pulsed sounds (which are more complex and varied than the whistles) are used "to avoid physical aggression in situations of high excitement", such as when they are competing for the same piece of food, for example. The dolphins emit these strident sounds when in the presence of other individuals moving towards the same prey. The "least dominant" one soon moves away in order to avoid confrontation. The bottlenose dolphin has a single blowhole located on the dorsal surface of the head consisting of a hole and a muscular flap. The flap is closed during muscle relaxation and opens during contraction. Dolphins are voluntary breathers, who must deliberately surface and open their blowholes to get air. They can store almost twice as much oxygen in proportion to their body weight as a human can. The dolphin can store 36 millilitres of oxygen per kilogram of body weight, compared with 20 millilitres per kilogram for humans. This is an adaptation to diving. The bottlenose dolphin typically rises to the surface to breathe through its blowhole two to three times per minute, although it can remain submerged for up to 20 minutes. Dolphins can breathe while "half-asleep". During the sleeping cycle, one brain hemisphere remains active, while the other hemisphere shuts down. The active hemisphere handles surfacing and breathing behavior. The daily sleeping cycle lasts for about 8 hours, in increments of minutes to hours. During the sleeping cycle, they remain near the surface, swimming slowly or "logging", and occasionally closing one eye. Adult males live mostly alone or in groups of two to three, and join pods for short periods of time. Adult female and young dolphins normally live in groups of up to 15 animals.
Predators or Prey?
Some large shark species, such as the tiger shark, the dusky shark, the great white shark and the bull shark, prey on the bottlenose dolphin, especially calves. The bottlenose dolphin is capable of defending itself by charging the predator; dolphin 'mobbing' behavior of sharks can occasionally prove fatal for the shark. The prey available to a dolphin vary with its geographic location. Coastal dolphins tend to eat fishes and bottom-dwelling invertebrates.•Offshore dolphins tend to eat fishes and squid.
Some large shark species, such as the tiger shark, the dusky shark, the great white shark and the bull shark, prey on the bottlenose dolphin, especially calves. The bottlenose dolphin is capable of defending itself by charging the predator; dolphin 'mobbing' behavior of sharks can occasionally prove fatal for the shark. The prey available to a dolphin vary with its geographic location. Coastal dolphins tend to eat fishes and bottom-dwelling invertebrates.•Offshore dolphins tend to eat fishes and squid.
Diet
Its diet consists mainly of small fish, crustaceans, and squid. Although this varies by location, many populations share an appetite for fish from the mullet family, the tuna and mackerel family, and the drum and croaker family. Its cone-like teeth serve to grasp, but do not chew food. When they encounter a shoal of fish, they work as a team to herd them towards the shore to maximize the harvest. They also hunt alone, often targeting bottom-dwelling species. The bottlenose dolphin sometimes hits a fish with its fluke, sometimes knocking it out of the water, using a strategy called "fish whacking". "Strand feeding", is an inherited feeding technique used by bottlenose dolphins near and around coastal regions of South Carolina. When a pod finds a school of fish, they will circle the school and trap the fish in a mini whirlpool. Then, the dolphins will charge at the school and push their bodies up onto a mud-flat, forcing the fish on the mud-flat as well. The dolphins then crawl around on their sides, consuming the fish they washed up on shore.
Its diet consists mainly of small fish, crustaceans, and squid. Although this varies by location, many populations share an appetite for fish from the mullet family, the tuna and mackerel family, and the drum and croaker family. Its cone-like teeth serve to grasp, but do not chew food. When they encounter a shoal of fish, they work as a team to herd them towards the shore to maximize the harvest. They also hunt alone, often targeting bottom-dwelling species. The bottlenose dolphin sometimes hits a fish with its fluke, sometimes knocking it out of the water, using a strategy called "fish whacking". "Strand feeding", is an inherited feeding technique used by bottlenose dolphins near and around coastal regions of South Carolina. When a pod finds a school of fish, they will circle the school and trap the fish in a mini whirlpool. Then, the dolphins will charge at the school and push their bodies up onto a mud-flat, forcing the fish on the mud-flat as well. The dolphins then crawl around on their sides, consuming the fish they washed up on shore.
Habitat
Bottlenose dolphins are very adaptable, so they can be found in cold temperate to tropical waters throughout the world. Two separate populations of Tursiops exist. One population is found inshore, in the shallow waters (under 30metres) along coastlines and the other population is found offshore, in deep ocean waters over 30 m.
Bottlenose dolphins are very adaptable, so they can be found in cold temperate to tropical waters throughout the world. Two separate populations of Tursiops exist. One population is found inshore, in the shallow waters (under 30metres) along coastlines and the other population is found offshore, in deep ocean waters over 30 m.
Conservation
Bottlenose dolphins are not endangered. Their future is stable because of their abundance and adaptability. However, specific populations are threatened due to various environmental changes. The population in the Moray Firth in Scotland is estimated to consist of around 150 animals, and is declining by around 6% per year from harassment, traumatic injury, water pollution and reduction in food availability. Likewise, an isolated population in Doubtful Sound, New Zealand, is in decline due to calf loss coincident to an increase in warm freshwater discharge into the fjord.
Bottlenose dolphins are not endangered. Their future is stable because of their abundance and adaptability. However, specific populations are threatened due to various environmental changes. The population in the Moray Firth in Scotland is estimated to consist of around 150 animals, and is declining by around 6% per year from harassment, traumatic injury, water pollution and reduction in food availability. Likewise, an isolated population in Doubtful Sound, New Zealand, is in decline due to calf loss coincident to an increase in warm freshwater discharge into the fjord.
Reproduction
During the breeding season, males compete for access to females. Such competition can take the form of fighting other males or of herding females to prevent access by other males. In Shark Bay, male bottlenose dolphins have been observed working in pairs or larger groups to follow and/or restrict the movement of a female for weeks at a time, waiting for her to become sexually receptive. These coalitions will fight with other coalitions for control of females. Mating occurs belly to belly. Dolphins have been observed engaging in intercourse when the females are not in their estrus cycles and cannot produce young, as well as when they can. The gestation period averages 12 months. Births can occur at any time of year, although peaks occur in warmer months. The young are born in shallow water, sometimes assisted by a (possibly male) "midwife", and usually only a single calf is born.Twins are possible but rare. Newborn bottlenose dolphins are between 0.8–1.4 m (2.6–4.6 ft) 9–30 kg (20–66 lb) kilograms, with Indo-Pacific bottlenose dolphin infants generally smaller than common bottlenose dolphin infants. To accelerate nursing, the mother can eject milk from her mammary glands. The calf suckles for 18 to 20 months, and continues to closely associate with its mother for several years after weaning. Females sexually mature at ages 5–13, males at ages 9–14.[1] Females reproduce every two to six years.
During the breeding season, males compete for access to females. Such competition can take the form of fighting other males or of herding females to prevent access by other males. In Shark Bay, male bottlenose dolphins have been observed working in pairs or larger groups to follow and/or restrict the movement of a female for weeks at a time, waiting for her to become sexually receptive. These coalitions will fight with other coalitions for control of females. Mating occurs belly to belly. Dolphins have been observed engaging in intercourse when the females are not in their estrus cycles and cannot produce young, as well as when they can. The gestation period averages 12 months. Births can occur at any time of year, although peaks occur in warmer months. The young are born in shallow water, sometimes assisted by a (possibly male) "midwife", and usually only a single calf is born.Twins are possible but rare. Newborn bottlenose dolphins are between 0.8–1.4 m (2.6–4.6 ft) 9–30 kg (20–66 lb) kilograms, with Indo-Pacific bottlenose dolphin infants generally smaller than common bottlenose dolphin infants. To accelerate nursing, the mother can eject milk from her mammary glands. The calf suckles for 18 to 20 months, and continues to closely associate with its mother for several years after weaning. Females sexually mature at ages 5–13, males at ages 9–14.[1] Females reproduce every two to six years.
