The Crayfish Fanclub Newsletter - February 1997
The Crayfish Fan Club Newsletter.
Welcome to the Crayfish Fan Club Newsletter.
I would like to take this opportunity to greet new members and to thank everyone for their contribution to the Crayfish Fanclub which you can send via email. Contribution ensures the continuation of the Crayfish Fan Club and the Crayfish Corner website. Please send your crayfish articles, pics, jokes, songs, stories and comments to me at the address below.
The information below is exclusive to Crayfish Fan Club members but will be posted on the Crayfish Corner in a few weeks after you receive this.
Crayfish News / Gossip
Hello to all our new members. The fanclub now has more than 20 members. Thanks to you all for your interest.
The Crayfish Corner has not been updated much - the new look is still in development
Crustaceans are largely aquatic invertebrate animals in the phylum Arthropoda, class Crustacea, and include the barnicle, the crab, CRAYFISH, the lobster, the shrimp, and terrestrial wood lice. Members of the class Crustacea, consisting of about 30,000 species, have evolved a variety of specialized body forms and behaviors to cope with both aquatic and terrestrial environments.
Crustaceans are characterized by a shell, or integument, formed by calcified cuticle, which includes glands and pigment granules called chromatophores. The head contains five pairs of appendages, including two pairs of sensory antennae (a distinguishing feature for the class), a pair of mandibles, and first and second maxillae used as mouthparts. The trunk consists of a thorax--often covered by a dorsal carapace, a cuticular extension of the head overhanging the body sides--and a variable number of appendages modified in different species for swimming, crawling, grasping, egg-brooding, and food manipulation. An abdomen follows, often with appendages and terminal fanlike segments, or uropods.
Feeding habits of crustaceans range from filter feeding to scavenging and from herbivorous to carnivorous, especially in larger species. A few species of crustaceans are internal or external parasites.
The generalized crustacean digestive system varies from a simple tube in primitive forms to a highly specialized system of chambers and diverticula, each with a specialized function in digestion. The circulatory system usually consists of a dorsal thoracic heart, tubular or spherical, from which blood is pumped to a system of arteries and open sinuses. In some groups the heart or arteries, or both, are absent. The nervous system shows a central, ladder-like arrangement of ganglia, with a concentration of ganglia in the head region, and a variety of complex peripheral sensory structures. Crustaceans usually mate through copulation, the male clasping the female with a specialized appendage.
Next month: An article from the Logan Cave National Wildlife Refuge