Atlantic Spotted Dolphin

Atlantic Spotted Dolphin

Kingdom
Phylum
Subphylum
Class
Order
Infraorder
Family
Genus
SPECIES
Stenella frontalis
Population size
Unknown
Life Span
30-40 yrs
WEIGHT
130-140 kg
LENGTH
1.7-2.3 m

This dolphin most frequently occurs in the clear and shallow waters around the Bahamas. By its appearance, the Atlantic spotted dolphin is an intermediate between pantropical spotted dolphin and the bottlenose dolphin. Despite the name, not all individuals of this species exhibit spots on their body, though many of them do. However, some dolphins are so densely spotted, that may seem to be completely white from afar. As a general rule, calf dolphins normally lack these spots, developing them as they grow up. On the other hand, those living in the far-offshore waters of the Gulf Stream are often smaller and without spots on their body.

Distibution

As the name of the species suggests, the dolphin is found in the Atlantic Ocean, occurring in the tropical, subtropical and warm temperate waters, namely: around the Azores, Canary Islands, Gabon and Brazil. The species is also widely distributed along the US East Coast, from Gulf of Mexico to Cape Cod (MA), consisting of 2 stocks: the Northern Gulf of Mexico Stock and the Western North Atlantic Stock. Those, living in the Bahamas, are most often seen in the shallow water above sand flats. On the whole, these dolphins normally prefer waters over the continental shelf, though in some areas the species can also be found in deep oceanic waters.

Atlantic Spotted Dolphin habitat map

Climate zones

Habits and Lifestyle

These highly social animals gather into groups known as pods. Members of a pod live in close relationships with each other and complex social organization, including individual recognition. Atlantic spotted dolphins are very careful to pregnant females and calves, fiercely protecting them from predators such as sharks. Member of a group also help each other to care for the calves. Within a pod, each individual is ranked depending on its gender, age, size and other factors. These dolphins may form very small groups, consisting of just a few individuals, and large pods of up to several thousand dolphins in offshore areas. However, pods of Atlantic spotted dolphins rarely include more than 50 animals. These dolphins have been seen peacefully moving around with other dolphin species. The Atlantic spotted dolphins are cooperative hunters: they usually hunt in groups at night, using a technique of encircling the prey. They use whistles, cackles, sharp cries and tongue clicking as forms of communication.

Group name

Diet and Nutrition

Atlantic spotted dolphins are carnivores (piscivores). Their usual diet primarily consists of bottom-dwelling invertebrates, squid as well as fish.

Mating Habits

MATING BEHAVIOR
REPRODUCTION SEASON
Year-round
PREGNANCY DURATION
11-12 months
BABY CARRYING
1 calf
INDEPENDENT AGE
1-5 years
FEMALE NAME
cow
MALE NAME
bull
BABY NAME
calf

These dolphins have polygynous mating system, where one male mates with a number of females. The Atlantic spotted dolphins mate throughout the year. The gestation period lasts for 11 - 12 months, yielding a single baby. The female usually gives birth with the interval of 1 - 5 years with an average of 3 years. The youngster is nursed by its mother for 1 - 5 years, becoming sexually mature and starting to breed at 8 - 15 years old.

Population

Population threats

Presently, the Atlantic spotted dolphin is threatened by hunting for food and bait along the South American and West African coasts of its habitat, especially in the Caribbean Sea. Besides, the species hugely suffers from fisheries across the area of its range: the dolphins are often entangled in fishing nets, which causes the notable number of mortality among Atlantic spotted dolphins.

Population number

According to the NMFS NOAA (National Oceanic and Atmospheric Administration) Fisheries resource, the total population size of the Atlantic spotted dolphin is unknown for today. However, there are estimates for specific populations of this species such as the northern Gulf of Mexico stock (24.500 – 31.000 individuals) and the western North Atlantic population (36.000 – 51.000 individuals). Currently, Atlantic spotted dolphins are classified as Data Deficient (DD) on the IUCN Red List.

Fun Facts for Kids

  • These playful dolphins love performing acrobatic tricks, and can often be seen leaping out of water or riding bow waves of boats.
  • The Atlantic spotted dolphins have a unique communication system. They interact through cries, whistles and various high-pitched calls. By means of these sounds, the dolphins can warn each other about threats, inform about a playful mood or a newly found food source. Meanwhile, each of the animals has its own frequency, which helps identify individual dolphins.
  • Along with calls, these dolphins communicate with each other through body language. Thus, they can frequently be seen bumping into one another. Besides, they often use spy hopping and leaping out of water in order to show their abilities, to inform others of different interests or to warn the members of the pod of various threats.
  • These dolphins can dive at a depth of 40-60 meters (130-200 feet) and are capable of staying submerged for up to 10 minutes. However, they rarely dive deeper than 10 meters (30 feet), usually remaining in the water from 2 to 6 minutes.
  • These animals use so-called "sonar" technique of communication, detecting objects through sound waves, which reflect off the object and return to the animal.
  • Members of a pod are very careful to each other, helping those in distress. When in trouble, a dolphin will call out for help, sending out a special intermittent distress call. Other dolphins will hear the call and rush to aid, usually caring for a wounded or sick individual by turns, until the dolphin recovers.

References

1. Atlantic Spotted Dolphin Wikipedia article - https://en.wikipedia.org/wiki/Atlantic_spotted_dolphin
2. Atlantic Spotted Dolphin on The IUCN Red List site - http://www.iucnredlist.org/details/20732/0

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