Brachiopoda is a group or class of mollusc-like animals, so named from the development of a long spirally-coiled, fringed appendage or arm on either side of the mouth serving as respiratory organs. They are bivalves, and in this respect they resemble the Lamellibranchiata. They have no proper power of locomotion, and remain fixed to submarine bodies, in some cases by a peduncle passing through an aperture at the 'beak'. They are widely diffused, and in the fossil state are interesting to the geologist by enabling him to identify certain strata. Research Brachiopoda
Cephalopoda is a class of Phylum mollusca. They are the squids and octopuses. They are the highest in organization in that division of the animal kingdom, characterized by having the organs of prehension and locomotion, called tentacles or arms, attached to the head. The arms are furnished with numerous suckers, and enable them to cling to and entangle their prey;
and they have a pair of well-developed jaws and eyes. They are divided into two sections, Tetrabranchiata (four-gilled) and Dibranchiata (two-gilled). The nautilus and the fossil genera Orthoceras, Ammonites, Goniatites, etc, belong to the Tetrabranchiata, in which the animal has an external shell. The dibranchiate group includes the argonaut, the octopus or eight-armed cuttlefishes, and the ten-armed forms, as the squids, the fossil belenmites, etc. The shell is in all these internal (being known as the 'pen' and the 'cuttle-bone'), in some rudimentary. The fossil Cephalopoda are multitudinous. Research Cephalopoda
Crab is a popular name for crustacea of the sub-order Brachyura and to many of the Anomura of the order Decapoda. The true crabs (Brachyura) are characterised by having a small abdomen and the head and breast are united, forming the cephalothorax, and the whole is covered with a strong carapace.
The mouth has several pairs of strong jaws, in addition to which the stomach has its internal surface studded with hard projections for the purpose of grinding the food. The stomach is popularly called the 'sand-bag'; a little behind it is the heart, which propels a colourless lymph (the blood) to the gills (' dead man's fingers'). The liver is the soft, rich yellow substance, usually called the fat of the crab. They 'moult' or throw off their calcareous covering periodically.
They have ten legs, of which the first pair are modified as claws, and the remaining pairs are used for locomotion. There are many genera, distinguished from the lobster and other macrurous or long-tailed decapods by the shortness of their tail, which is folded under the body. Their eyes are compound, with hexagonal facets, and are pedunculated, elongated, and movable. Like most individuals of the class, they easily lose their claws, which are as readily renewed. They are generally scavengers, living on decaying animal matter, though others live on vegetable substances, as the racer-crabs of the West Indies, which suck the juice of the sugar-cane.
Most crabs inhabit the sea, others fresh water, some the land, only going to the sea to spawn. Of the crabs several species are highly esteemed as an article of food, and the fishery constitutes an important trade on many coasts. The large edible crab (Cancer pagurus) is common on the British shores, and is much sought after. Research Crab
The Echinus (Sea-Urchins or Sea-Eggs) are a genus of marine animals, the type of an order (Echinoidea) of the class Phylum Echinodermata. The body is more or less globular and covered with a test or shell, often beset with movable spines. Locomotion is effected by a singular system of ainbulacra or 'tube-feet', which are distended with water, protruded through pores, and again retracted. The mouth is situated on the inferior surface, generally in the centre, is armed with calcareousteeth, and opens into a gullet conducting to a distinct stomach. The stomach has issue into a convoluted intestine which winds round the interior of the shell and terminates in a distinct anus. The anus varies in position, being sometimes on the apical disc and sometimes marginal. The Echinus esculentus and some other species are edible. Research Echinus
The elephant-shrew or jumping-shrew (Macroscelides) is a small insectivorous mammal, of which there are several species, all found in Africa. They are ground animals, nocturnal in habit, and receive their first common name from their prolonged snouts, and their second from their method of locomotion. The jumping movements are facilitated by the length of the hind legs. Research Elephant-Shrew
The ophiuroidea are a subclass of stelleroidea. They are the brittle stars. They have a flattened body clearly marked into two regions; the disc and the arms. Tube feet extend from the under surface of the arms, but the groove is closed to form a tube. Locomotion is chiefly by muscular movement of the arms assisted by the feet. Research Ophiuroidea
The pectoral fins are a pair of fins situated just behind the head in fishes that help to control the direction of movement during locomotion. Research Pectoral fins
A tail is the prolongation of the back-bone in vertebrate animals. It is a portion of the body containing no viscera but consisting solely of bone and muscle. Tails are organs of locomotion in fishes, serve as grasping organs in some monkeys, are weapons of defence in some animals, of offence in some other animals and serve as balancers in some other animals such as kangaroos.
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Locomotion
