Fleas are wingless members of the order, and their agility fully compensates for the loss of the power of flight. There are many species, infesting different mammals and birds. The females of the tiny sand-fleas, or chiggers (Sarcopsylla penetrans), of America deposit their eggs in the feet of human beings (or other animals), and unless the painful swellings thus brought about are carefully treated they are apt to fester dangerously.
STRANGE ANIMAL FORMS FOUND IN THE SEA
| SEA CUCUMBERS (See [Page 242]) | SURFACE OF STARFISH (See [Page 242]) |
| SNAKE-STAR (See [Page 242]) | JELLY-FISH ([Page 243]) | HEART-SHAPED SEA URCHIN (See [Page 242]) |
| SEA ANEMONE (See [Page 243]) | SEA URCHIN (See [Page 242]) | BRANCHING CORAL ([Page 243]) |
STARFISHES AND SEA-URCHINS (Echinoderms)
HEDGEHOG SKINNED ANIMALS OF THE SEA. SEA-LILIES, STAR
FISHES, BRITTLE STARS, SEA URCHINS, AND SEA CUCUMBERS
Echinoderms, or hedgehog-skinned animals differ from all the forms so far considered in the nature of their symmetry. Instead of being two-sided, with a well-marked distinction between right and left and front and back (bilateral symmetry), they resemble a star or regular flower in shape. The skin is hardened by the deposition of salts of lime, and the body is often covered with spines, as more particularly in sea urchins.
Five existing subdivisions are recognized: (1) Sea-lilies and feather-stars (Crinoidea); (2) Starfishes (Asteroidea); (3) Brittle Stars (Ophiuroidea); (4) Sea urchins (Echinoidea); and (5) Sea-cucumbers (Holothuroidea). All are marine.