| Libinia dubia | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Brachyura |
| Family: | Epialtidae |
| Genus: | Libinia |
| Species: | L. dubia |
| Binomial name | |
| Libinia dubia | |
Libinia dubia, the longnose spider crab, is a species of crab in the family Epialtidae. It is found in shallow waters on the eastern coast of North America.
The carapace of the longnose spider crab is nearly circular in outline. The shell grows to an average diameter of 6 to 10 centimetres (2.4 to 3.9 in) with the males being larger than the females. There are about six spiny protuberances on each edge of the shell and another six down the midline. The upper surface is covered with short setae (bristles) which are hooked and resemble velcro. To these the crab sticks pieces of seaweed and other organisms as camouflage. [3] There are two small stalked eyes and between these the carapace extends forward in a forked rostrum. There are five pairs of long, thin, jointed walking legs. The front pair end in rather small pincers and the terminal joint of the others legs is a curved claw. The longnose spider crab may be confused with the portly spider crab, Libinia emarginata , but that species usually has nine spines on the margin at each side of the shell. [3]
The longnose spider crab is found on the eastern seaboard of the United States at depths down to about 50 metres (160 ft). The range is from Cape Cod to southern Texas, including Cuba and the Bahamas. In the Indian River Lagoon, adults are found on sandy bottoms and juveniles in seagrass meadows. In the late 1900s this crab was identified off the coast of Tunisia, but by what means it had managed to cross the Atlantic Ocean is unclear. [4]
When breeding, the male transfers bundles of sperm called spermatophores to the female. Fertilisation is internal and afterwards the female broods the eggs under her abdomen until they hatch. The larvae then become part of the zooplankton, having two zoeal stages and one megalopal or post-larval stage. After that the larvae settle on the sea bed and undergo metamorphosis into juvenile crabs. [3]
The longnose spider crab is a scavenger and detritivore. In seagrass meadows it eats the seaweeds that grow there. It is eaten by predatory fish such as the pinfish (Lagodon rhomboides), the gag grouper (Mycteroperca microlepis) and the oyster toadfish (Opsanus tau). It attempts to avoid being eaten by sticking unpalatable seaweeds and invertebrates onto its carapace. [3] These include the brown alga, Dictyota menstrualis and the sun sponge ( Hymeniacidon heliophila ). Along the East Coast of the US, where Dictyota menstrualis is present, these crabs recognize and preferentially select this chemically noxious algae. However, in places where the D. menstrualis is absent, L. dubia has an alternative camouflage method and does not appear to recognize the D. menstrualis. [5] As it grows larger it no longer needs to disguise itself in this way because its shell is too large for the predators to ingest. [3] It is sometimes associated with the loggerhead turtle (Caretta caretta), living as an epibiont on its carapace. [6]
Longnose spider crabs are often found living inside the bells of cannonball jellies, Stomolophus meleagris . [3] It is thought they gain access as juveniles when the jellyfish happens to drift near the seabed or possibly they may metamorphosise from larvae directly inside the bell. It may be a symbiotic relationship with the crabs gaining protection from predators and obtaining food from their hosts but any benefit to the jellyfish is unclear, especially as its tissues may be nibbled. [7]
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land, are generally covered with a thick exoskeleton, and have a single pair of pincers on each arm. They first appeared during the Jurassic period, around 200 million years ago.
Libinia emarginata, the portly spider crab, common spider crab or nine-spined spider crab, is a species of stenohaline crab that lives on the Atlantic coast of North America.
The Japanese spider crab is a species of marine crab and is the biggest one that lives in the waters around Japan. At around 3.7 meters, it has the largest leg-span of any arthropod. The Japanese name for this species is taka-ashi-gani,, literally translating to “tall legs crab”. It goes through three main larval stages along with a prezoeal stage to grow to its great size.
Stenorhynchus seticornis, the yellowline arrow crab or simply arrow crab, is a species of marine crab.
The loggerhead sea turtle is a species of oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around 90 cm (35 in) in carapace length when fully grown. The adult loggerhead sea turtle weighs approximately 135 kg (298 lb), with the largest specimens weighing in at more than 450 kg (1,000 lb). The skin ranges from yellow to brown in color, and the shell is typically reddish brown. No external differences in sex are seen until the turtle becomes an adult, the most obvious difference being the adult males have thicker tails and shorter plastrons than the females.
Grapsus grapsus is one of the most common crabs along the western coast of the Americas. It is known as the red rock crab, or, along with other crabs such as Percnon gibbesi, as the Sally Lightfoot crab.
The graceful rock crab or slender crab, Metacarcinus gracilis or Cancer gracilis, is one of only two members of the genus Metacarcinus, recognized by WoRMS, whose chelae (claws) are white tipped, the other crab being M. magister. Both of these eastern Pacific crab species are recognized by ITIS as belonging to the much larger genus Cancer. M. gracilis has been caught from Alaska to Bahía Magdelena, Baja California. Although M. gracilis is only found in the Pacific Ocean, it has cousins in the Atlantic Ocean. The genus Cancer apparently evolved in the Pacific Ocean and later migrated to the Atlantic Ocean. Larvae and small juveniles of this species are often seen riding jellyfish, especially Phacellophora camtschatica. The juvenile crabs steal food from the jellyfish and also clean off parasitic amphipods.
Notomithrax ursus, known as the hairy seaweed crab, is a spider crab of the family Majidae.
Decorator crabs are crabs of several different species, belonging to the superfamily Majoidea, that use materials from their environment to hide from, or ward off, predators. They decorate themselves by sticking mostly sedentary animals and plants to their bodies as camouflage, or if the attached organisms are noxious, to ward off predators through aposematism.
Xantho poressa, the jaguar round crab, is a species of crab from the eastern Atlantic Ocean. It is one of four species in the genus Xantho.
Amarinus lacustris is a species of freshwater crab from Australia, New Zealand and nearby islands, where it lives in water of various salinities. It grows up to 10 mm (0.4 in) wide, with an H-shaped groove on its back. It is an omnivore and is eaten by crayfish and fish. It was first discovered in Lake Pupuke, near Auckland, and is the only freshwater crab in New Zealand.
Guinotellus melvillensis is a species of crabs in the family Xanthidae, the only species in the genus Guinotellus. It is a benthic crab with an ovate carapace within the subfamily Euxanthinae.
Oregonia gracilis, commonly known as the graceful decorator crab, is a species of crab belonging to the family Oregoniidae. Like other decorator crabs it habitually attaches other organisms to its back. The sessile organisms are attached to hooked setae that act as a sort of velcro attachment. This decoration provides visual and chemical camouflage thus reducing predation risk. Pacific halibut are a major predator of O. gracilis. Other predators include octopus and sea otters. The main food source of O. gracilis is floating kelp and algae that they capture utilizing a waiting strategy in order to maintain cryptosis.
Libinia ferreirae is a species of tropical spider crab in the family Epialtidae. It is found on the seabed in shallow waters off the Atlantic coast of South America.
Planes minutus is a species of pelagic crab that lives in the North Atlantic Ocean. It is typically less than 10 mm (0.4 in) long across the back, and is variable in colouration, to match its background. It may have been the crab seen by Christopher Columbus on Sargassum weed in the Sargasso Sea in 1492.
Portunus sayi, the sargassum swimming crab, is a species of pelagic crab in the family Portunidae. It is found in the western Atlantic Ocean and the Caribbean Sea where it makes its home among floating mats of Sargassum seaweed. It was named in honour of the American naturalist Thomas Say.
Ocypode convexa, commonly known as the golden ghost crab, or alternatively the western ghost crab or yellow ghost crab, is a species of ghost crabs endemic to the coast of Western Australia, from Broome to Perth. They are relatively large ghost crabs, with a carapace growing up to 45 mm (1.8 in) long and 52 mm (2.0 in) wide. They are easily recognisable by their golden yellow colouration. Like other ghost crabs they have box-like bodies with unequally sized claws. They also have large eyestalks with the cornea occupying most of the bottom part.
Hyastenus hilgendorfi is a species of spider crab from the family Epialtidae, classified in the sub-family Pisinae, from the Indo-Pacific region. It has been recorded in the Suez Canal and there have been a few records in the eastern Mediterranean, making it a Lessepsian migrant.
Paguristes eremita, the eye spot hermit crab, is a species of hermit crab in the family Diogenidae. It is found in the Mediterranean Sea.
Libinia spinosa is a majoid crab found in mud and sand bottoms of the Southwestern Atlantic and Pacific oceans. It is a generalist feeder on organisms such as algae, sponges, cnidarians, mollusks, polychaetes, crustaceans, and small fish. It commonly engages in a symbiotic relationship with the medusa Lychnorhiza lucerna.