Dolpin (4) Flashcards
(30 cards)
What is a common misconception about the common name of the white-beaked dolphin?
Common names can be misleading; some may have a gray or dark beak.
What is the geographical significance of the white-beaked dolphin?
It is the northernmost member of a worldwide genus.
How do white-beaked dolphins do in captivity?
No white-beaked dolphin has been kept in captivity successfully, so we don’t know!
What is known about the white-beaked dolphin’s swimming ability (Hint: what sort of wake do they create)?
They are such fast swimmers that they create a ‘rooster tail’ wake.
True or False: White-beaked dolphins are known to ride bow waves of vessels.
False - for some reason, they don’t like to follow boats.
Why are white-beaked dolphin calves so big?
Because of all the blubber - they need it as they’re born into cold water.
- What is a common herd size for White-beaked dolphins?
- How big can their pods be?
- Groups of 6 to 10 are quite common
- Pods can be as large as 1,500 individuals.
Where is the distribution of White-beaked dolphins restricted to?
Coastal regions of the North Atlantic Ocean from New England east to the Barents Sea and the North Sea
What period did the transition of certain mammals back into water occur?
Between 70 million and 50 million years ago.
What are the characteristics of the early mammals that adapted to aquatic life (4 Points)?
Size, number of legs, warm or cold blooded, foetal companion
- Pig-sized
- Four-legged
- Warm-blooded
- Placental creatures.
Name the two groups of cetaceans.
- Odontoceti (toothed whales)
- Mysticeti (baleen whales)
What adaptations did Odontoceti develop?
Specialized teeth to grasp fish and other relatively large prey.
What adaptations did Mysticeti develop?
Lost their teeth and developed large mouths with baleen to trap small organisms.
What group of land mammals are believed to be ancestors of cetaceans?
Creodonts.
True or False: Both groups of cetaceans evolved superficially similar body forms due to similar environmental demands.
True.
What ecological environment did the earliest and most primative cetaceans inhabit?
Shallow waters of the ancient eastern Tethys Sea (which was present during the Triassic).
What has a larger brain: a dolphin or a human?
A dolphin!
What is the scientific name for toothed whales?
Odontoceti
How many species are generally recognized within the Odontoceti/toothed whales?
72
What is the family Physeteridae known for?
Large, deep-diving, gregarious sperm whales
What are Delphinidae commonly referred to as?
True dolphins
Which family of whales has a single highly specialized tooth that forms a long spiral tusk?
Monodontidae (this includes the narwhal)
What are the three main hunting strategies used by toothed-whales?
- Oceanic deep divers
- Oceanic near-surface feeders
- Inshore habitat occupants
How far can the giant sperm whale dive?
Over 3,000m!
