Prominent among the family Ursidae is a polar bear that is adapted to a highly specialized semi-aquatic lifestyle. Although it is a bear yet it is listed as a marine mammal precisely due to the fact that it spends 50% of its life on ice floes and is able to swim as far as 90 km (60 miles).
urchin. 1  a mischievous boy. 2  any small boy or youngster. 3  sea urchin. 4  either of two small rollers covered with card clothing used in conjunction with the cylinder in carding. 5  Chiefly British Dialect. a hedgehog. 6  Obsolete. an elf or mischievous sprite.
Body of sea urchins has radial symmetry. That means that each sea urchin can be divided in five equal parts. Color of sea urchins depends on the species. Majority of species are black, brown, purple, red or green in color. Sea urchins have 5 rows of paired tube feet on the bottom side of the body.They end with suckers which facilitate adhesion to rocks, hunt and movement on the ocean floor.hat means that each sea urchin can be divided in five equal parts. Color of sea urchins depends on the species. Majority of species are black, brown, purple, red or green in color. Sea urchins have 5 rows of paired tube feet on the bottom side of the body.