Read each sentence and identify the word/phrase that you believe correctly completes the statement. Then, click on the arrow to see if your answer is correct.
1. The two largest groups of marine reptiles are the and .
2. Seabirds have feet, shorebirds do not.
3. With only a few exceptions, mammals are because their embryos develop in the female's womb. Embryos of most mammals receive nutrients and oxygen across the , a membrane connecting the embryo to the womb.
4. The pinnipeds include the seals, sea lions, and walruses. Sea lions can be distinguished from seals by their ears and/or that can move forward.
5. Unlike other marine mammals, sea otters lack and rely on their rich fur for insulation.
6. Sirenians (dugongs and ) look like oversized pinnipeds but lack a pair of limbs.
7. Toothless, or whales, are filter-feeding cetaceans. Most filter out plankton, especially .
8. Most cetaceans are whales, which include the dolphins and porpoises.
9. Marine mammals are excellent divers as the result of several adaptations. These include the storage of additional oxygen in the blood and muscles, the collapse of the , and the direction of the to the brain and other vital organs during diving.
10. in many cetaceans involves producing waves and analyzing their echo.
11. Complex behaviors among cetaceans include communication by means of and signals, play behavior, and of individuals in danger.
12. Many cetaceans and pinnipeds migrate every year from feeding to breeding areas. In most of the great whales, breeding areas are located in (or ) regions.
13. Pinnipeds prolong the development of their embryos by .
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