Dolphins arev small toothed cetaceans a group of marine maqmmals that evolved-----
Answers
Answer:
Dolphins evolved from land mammals whose legs were underneath their bodies.
Answer:
Dolphins are small-toothed Cetaceans, a group of marine mammals that evolved ______ land
mammals. They have developed numerous adaptations that make them well suited for life in water
including a streamlined body, flippers, blowholes and a layer _______ blubber for insulation. Dolphins
have curved beaks which means they appear to have permanent smiles.
Dolphins evolved from land mammals whose legs were underneath their bodies. As a result, dolphins
tails move up and down as they swim, whereas a fish’s tail moves _______ side to side.
Dolphins, like all toothed whales, lack olfactory lobes and nerves. Because dolphins do not possess
these anatomical features, they most likely have a poorly developed sense _______ smell.
The snout of some oceanic dolphins is long and slender due to their elongated, prominent jaw bones.
Within the dolphins' elongated jaw bone sits numerous conical teeth (some species have as many as
130 teeth in each jaw). Species that have prominent beaks include, for example, Common Dolphin,
Bottlenose Dolphin, Atlantic Humpbacked Dolphin, Tucuxi, Long-Snouted Spinner Dolphin, and
numerous others.
The forelimbs of a dolphin are anatomically equivalent _______ the forelimbs of other mammals (for
example, they are analogous to arms in humans). But the bones _______ the forelimbs of dolphins
have been shortened and made more rigid _______ supporting connective tissue. Pectoral flippers
enable dolphins _______ steer and modulate their speed.
The dorsal fin of a dolphin (located on the back of the dolphin) acts as a keel when the animal swims,
giving the animal directional control and stability within the water. But not all dolphins have a dorsal
fin. For example, the Northern Rightwhale Dolphins and the Southern Rightwhale Dolphins lack dorsal
fins.
Dolphins do not have prominent external ear openings. Their ear openings are small slits (located
behind their eyes) which do not connect to the middle ear. Instead, scientists suggest that sound is
conducted _______ the inner and middle ear by fat-lobes located by the lower jaw and _______
various bones _______ the skull.
Habitat and Distribution
Many dolphins inhabit coastal areas or areas _______ shallower water. While most dolphins prefer
warmer tropical or temperate waters one species, the orca (sometimes called killer whale) lives
_______ both the Arctic Ocean and the Antarctic Southern Ocean. Five dolphin species prefer fresh to
salt water; these species inhabit rivers _______ South America and South Asia.
Diet and Behavior
Dolphins are carnivorous predators. They use their strong teeth _______ hold their prey, but then either
swallow their prey whole tear it _______ small pieces. They are relatively light eaters; the bottlenose
dolphin, for example, eats about 5 percent of its weight each day.
Many species of dolphins migrate _______ find food. They consume a wide range of animals including
fish, squid, crustaceans, shrimp, and octopus. The very large Orca dolphin may also eat marine
mammals such as seals or marine birds such as penguins.
Many dolphin species work as a group _______ herd or coral fish. They may also follow fishing
vessels _______ enjoy the "waste" thrown overboard. Some species will also use their flukes _______
beat and stun their prey.
What was the most interesting piece of information about dolphins for you in the text?