Anatomy
The basic body plan of a horseshoe crab consists of three parts: the prosoma, the opisthosoma and the telson. The prosoma is the dome-shaped part at the front. The marginally-spined middle is called the opisthosoma, and the rear extension that looks like a spike is the telson, which is commonly described as the 'tail'. Contrary to popular belief, the telson is used to turn itself right side up when overturned. The mangrove horseshoe crab grows up to 40 centimeters in length (including the tail), and its whole body is protected by a hard, dark brown carapace. Uncommon for chelicerates, horseshoe crabs have two compound eyes. The main function of these compound eyes is to find a mate. In addition, they have two median eyes, two rudimentary lateral eyes, and an endoparietal eye on their carapace and two ventral eyes located on the underside by the mouth. Scientists believe the two ventral eyes aid in the orientation of the horseshoe crab when swimming. Each individual has six pairs of appendages. The first pair, the chelicerae, is used to place food in its mouth. The next pair of legs are the pedipalps, which are used for walking. The rest of the legs are used for locomotion and are known as pusher legs. Located behind their legs are book gills. These gills are used for propulsion to swim and to exchange respiratory gases.
Read more about this topic: Mangrove Horseshoe Crab
Famous quotes containing the word anatomy:
“Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world.”
—Ralph Waldo Emerson (1803–1882)
“I love to see, when leaves depart,
The clear anatomy arrive,”
—Roy Campbell (1902–1957)
“But a man must keep an eye on his servants, if he would not have them rule him. Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world. But it is found that the machine unmans the user. What he gains in making cloth, he loses in general power.”
—Ralph Waldo Emerson (1803–1882)