Lobster-Cherax destructor-australia
CheraxDestructorBlue.jpg
Anatomy
These fascinating crustaceans are from the order Decapoda. A decapods body is composed of a series of hard segments called somites. These somites are either fused together, or linked by a flexible join forming the limbs. They have two sets of jaws in front of the mouth, and have several appendages near the mouth that act as feeding aids. The limbs usually start with a pair of developed arms with claws. Behind these are 4 pairs of walking legs, and as the claws are classed as legs they total 10, hence Decapoda.
Some shrimps use the legs under the abdomen for swimming. However the true 'long tailed decapods', like all crayfish and some shrimp, can only swim backwards using the tail, not the pleopods. They are also used to fan freshwater to the gills (and may even bear gills themselves), food to the mouth, and females use these pleopods to carry their eggs.
The antennae and atennules in front of the mouth are their sensory organs (less developed in crabs), and they aid swimming and feeding in their larvae forms, the smaller pair contain fluid sacks used to orientate the animal (much like our inner ear). The large pair of antenna are very mobile and sensitive, and enable them to move safely through even the darkest waters. The antenna also hold the taste cells (aesthetasks). Their sense of touch is further enhanced by fine bristles situated on their limbs, allowing them to sense even the slightest movement.
Their eyes are usually situated on stalks, they are complex faceted eyes. There are between 7,000 and 30,000 individual eyes (onmatids) on each eyestalk. Even with these compound eyes, they principally orientate themselves by touch.
The body is covered with a solid shell primarily made up of chitin, but also contains some calcium carbonate for strength (especially in crabs). This shell is held together by an underlying layer of skin (the endoskeleton), and together forms the crustaceans exoskeleton. Its muscles are also attached to this outer shell.
In crabs, the abdomen is short and the telson is flat and folded underneath the body. The swimming legs and tail are lost altogether.
Anatomy
These fascinating crustaceans are from the order Decapoda. A decapods body is composed of a series of hard segments called somites. These somites are either fused together, or linked by a flexible join forming the limbs. They have two sets of jaws in front of the mouth, and have several appendages near the mouth that act as feeding aids. The limbs usually start with a pair of developed arms with claws. Behind these are 4 pairs of walking legs, and as the claws are classed as legs they total 10, hence Decapoda.
Some shrimps use the legs under the abdomen for swimming. However the true 'long tailed decapods', like all crayfish and some shrimp, can only swim backwards using the tail, not the pleopods. They are also used to fan freshwater to the gills (and may even bear gills themselves), food to the mouth, and females use these pleopods to carry their eggs.
The antennae and atennules in front of the mouth are their sensory organs (less developed in crabs), and they aid swimming and feeding in their larvae forms, the smaller pair contain fluid sacks used to orientate the animal (much like our inner ear). The large pair of antenna are very mobile and sensitive, and enable them to move safely through even the darkest waters. The antenna also hold the taste cells (aesthetasks). Their sense of touch is further enhanced by fine bristles situated on their limbs, allowing them to sense even the slightest movement.
Their eyes are usually situated on stalks, they are complex faceted eyes. There are between 7,000 and 30,000 individual eyes (onmatids) on each eyestalk. Even with these compound eyes, they principally orientate themselves by touch.
The body is covered with a solid shell primarily made up of chitin, but also contains some calcium carbonate for strength (especially in crabs). This shell is held together by an underlying layer of skin (the endoskeleton), and together forms the crustaceans exoskeleton. Its muscles are also attached to this outer shell.
In crabs, the abdomen is short and the telson is flat and folded underneath the body. The swimming legs and tail are lost altogether.
posted by rezats | 6:59 PM
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