- Limulidae
image_width = 200px
image_caption = "Pair of horseshoe crabs"
regnum =Animal ia
phylum =Arthropod a
subphylum =Chelicerata
classis =Xiphosura
ordo = Xiphosurida
familia = Limulidae
subdivision_ranks = Genera
subdivision =
*"Carcinoscorpius "
*"Limulus "
*†"Mesolimulus
*"Tachypleus "Limulidae is the only recent
family of the order Xiphosurida and contains all the 4 livingspecies known of the classXiphosura , formerly calledMerostomata . The best known species is thehorseshoe crab ("Limulus polyphemus"), whose ancestors can first be seen in theDevonian period's fossil record. They are found along the northwesternAtlantic coast and in theGulf of Mexico . Horseshoe crabs are found in shallow water on soft sandy bottoms.Anatomy
The entire body of
horseshoe crab is protected by a hard, dark brown carapace. They have two largecompound eye s and multiple smaller simple ones atop the carapace. Beneath the carapace they look quite similar to a largespider . They have five pairs of legs for walking, swimming and moving food into the mouth. Behind their legs, they have book gills, which exchange respiratory gases and are also occasionally used for swimming. While they can swim upside down, they usually are found on the ocean floor searching for worms andmollusk s, which are their main food. They may also feed oncrustacean s and even smallfish .Breeding
In the spring,
Horseshoe crabs migrate to certain shallow coastal waters. Males select a female and cling onto her back. The female digs a hole in the sand and lays her eggs while the male fertilizes them. The female can lay between 60,000-120,000 eggs in batches of a few thousand at a time. The eggs take about 2 weeks to hatch. The larvae continue to molt six times during the first year. It takes 11 years to reach sexual maturity, after which they may live up to 14 more years.Trivia
*Horseshoe crabs were formerly harvested for use as fertilizer. Currently they are harvested for their blood, which contains a chemical called
Limulus amebocyte lysate (LAL) that is used to detectpathogen s and their endotoxins, and used as bait for the eel and conch fisheries.*The other three species of this subclass are found along
Asia n coasts fromJapan andKorea , down to thePhilippines and inIndia .
Wikimedia Foundation. 2010.