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.
Sea urchin has special type of mouth, called Aristotle's lantern. Mouth is equipped with five sharp teeth that are able to drill a hole in the rock. Sea urchins are omnivores (they eat both plants and animals).Sea weed, algae, plankton and decaying organic matter are usually on the menu of sea urchins.ea urchin has special type of mouth, called Aristotle's lantern. Mouth is equipped with five sharp teeth that are able to drill a hole in the rock. Sea urchins are omnivores (they eat both plants and animals).