Of
all the invertebrate phyla, Arthropoda is the largest. There are more
than a million species, most of them being insects, and they live in almost
every habitat that supports life. The most important characteristic of
the Arthropods are their external skeletons. The exoskeleton is made of
a hard substance called chitin and protects the animals insides from damage.
It may be thick or thin, even calcified as in crabs. Although it protects
the animal, it restricts growth, so the animal must shed its exoskeleton
and secrete a new one in order to grow. This process is called molting.
Arthropods have segmented bodies, such as the head, thorax and abdomen.
The head and thorax may be fused together in some groups and are covered
by a single plate called the carapace. They also have jointed appendages
which allows them to move more freely. Arthropods have bristles on their
body which are very sensitive to touch, odor, taste, sound and currents.
Almost all marine Arthropods have gills used for respiration.
Of
all the invertebrate phyla, Arthropoda is the largest. There are more
than a million species, most of them being insects, and they live in almost
every habitat that supports life. The most important characteristic of
the Arthropods are their external skeletons. The exoskeleton is made of
a hard substance called chitin and protects the animals insides from damage.
It may be thick or thin, even calcified as in crabs. Although it protects
the animal, it restricts growth, so the animal must shed its exoskeleton
and secrete a new one in order to grow. This process is called molting.
Arthropods have segmented bodies, such as the head, thorax and abdomen.
The head and thorax may be fused together in some groups and are covered
by a single plate called the carapace. They also have jointed appendages
which allows them to move more freely. Arthropods have bristles on their
body which are very sensitive to touch, odor, taste, sound and currents.
Almost all marine Arthropods have gills used for respiration.