| Cyclograpsus lavauxi | |
|---|---|
 | |
| In a tidal rock pool | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Brachyura |
| Family: | Varunidae |
| Genus: | Cyclograpsus |
| Species: | C. lavauxi |
| Binomial name | |
| Cyclograpsus lavauxi (H. Milne-Edwards, 1853) | |
The smooth shore crab (Cyclograpsus lavauxi) is a marine large-eyed crab of the family Grapsidae, found in New Zealand and the Juan Fernández Islands of Chile. [1]
Cyclograpsus lavauxi is a small, temperate crab in the Grapsidae family. [2] The adult males average 28 mm and females average 26 mm. [1] The shell, or carapace, is polished [3] and is wider than it is long. [4] On average, the crab is 9 mm long and has a width of 11 mm. [5] The brim of the C. lavauxi carapace is smooth. [3] The anterior of the carapace is linear-edged, with two eye orbits, which are curved and situated in the two frontal corners. The antennae are well-developed and are used for sensing texture, food, and sound. [6] C. lavauxi has eight legs and two large frontal pincers. Its legs are compressed, slender, and long, and have six lines of hair running the full 4mm length of the legs, which are fairly robust. [5] The first, second, and third legs also have small tufts of hair between them. [4] Its long legs enable it to run at rapid speeds. C. lavauxi is agile and alert, resulting in a very mobile and versatile crab. [7]
A number of different color morphs have been observed in C. lavauxi. Their carapace can vary in color between slate blue, bluish-grey, fawn, and yellowish-brown. [1] C. lavauxi carapaces can also contain several shades of grey, green, and brown, often with dark brown and red speckles. [5] The underside of the crab is a lighter plain color than the carapace. [1] The legs display the same coloring as the carapace with brighter speckled colouring. [4]
The smooth shore crab's natural range is New Zealand and Chile in the Juan Fernandez Islands. [1] [8] C. lavauxi has been found to reside in a number of New Zealand sites from the Hohoura Harbour to Westland [1] with significant populations in the North Island. [5]
C. lavauxi can be found in a variety of environments, [9] including boulders, under stones, and on beaches ranging from exposed shores to protected bays. [1] It is a common crab on New Zealand beaches, outnumbering the larger common rock crab species. [1] It is found near the littoral sea margin, where it is only barely or not at all [10] wetted. It has also been discovered on mudflats, estuaries, and rocky coastlines. [11] Younger crabs prefer the lower lines of the shoreline and mudflats, whereas older crabs prefer the higher lines of the foreshore and mudflats. During the summer, all C. lavauxi migrate to the lower foreshore line. [2]
The mating season of C. lavauxi is during the summer months from mid-October to late December. [12] This mating season is highly synchronous within the population. The crabs are not monogamous, and both females and males will mate multiple times during the breeding season. [13] During this reproduction season, male-male competition is frequently displayed. Bigger males will often attack other males in the process of mating with a female, frequently giving the female an opportunity to escape. [13] Likely due to this competition, mating pairs can be found under rocks to hide from other males who might interfere. [13]
During mating, males approach a female and hold on to her carapace for an hour, after which there is a two-hour-long copulation. [13] Oftentimes females will resist males and try to escape. [13]
Females carry eggs between November and February [14] and have a short reception time of fewer than 24 hours, or almost a week in captivity. [13] They oviposit their eggs in synchronization with others in the population within a four-week period, [13] laying thousands of eggs in each batch. [14] Females who are unable to mate during the breeding season are able to lay fertile eggs by storing sperm from the previous breeding season. [13] This extra sperm is stored in the spermatheca after mating. [13] Females only lay eggs once per mating season. [12]
The eggs initially are a dark purple colour, but grow paler and develop black eyespots as they mature. [12] The eggs are 0.25-0.3 mm in diameter and hatch in about two months. [14] Once hatched, the larvae are just over 1 mm in length. [12]
C. lavauxi tend to moult soon after the breeding season has ended, in late summer to early autumn. [13]
C. lavauxi is a scavenger crab, foraging on deceased animals and plants, [3] although in most cases it is a herbivore. [5] Its general diet includes algae, drift and seaweed. [1] The crabs feed only during high tides, and are able to synchronize or modify their feeding pattern to ensure they feed under optimal conditions, maximizing their feeding hours and nutrition intake. [9]
A number of species predate on C. lavauxi, particularly bird species, due to the crabs' inhabiting the area where the tide does not often reach. [15] Their main predators are generalist birds such as Gulls and Kingfishers. [9] Fish species including the Smooth Hound Fish, Spiny Dogfish, Terakihi, Sea Perch, Moki and Red Gurnard also occur. [16] C. lavauxi are at times able to evade predators by using their quick reactions and speed. [15]
The nematode Ascarophsis sp. and the parasitic isopod Portunion sp. are found in C. lavauxi. [17] The majority of C. lavauxi are infected by the internal parasite Portunion sp. Brockerhoff's study showed the reproduction of female C. lavauxi was remarkably reduced by the parasite Portunion sp., this was believed to be because all parasitized females were castrated, although there were no visible signs of this parasite affecting mating behaviour in the males. [18] The male verse male competition was also not seen to affect the crab that was infected with the parasite Portunion sp. Studies also suggest that females do not avoid either the unparasitized and parasitized males due to there being no visible disadvantages to either. [18]
C. lavauxi has the ability to live successfully under large amounts of sediment and often more successfully than others within its genus. C. lavauxi displays a number of other unique behavioural traits including its aggressiveness when cornered, raising its pincers to accentuate its size along with showing their paleness. [1] The common body posture of C. lavauxi is being flat with pincers folded and lying on the ground with its walking legs close and side-by-side. When in a raised position, it places its body at a 45 degree angle with its back part still lying on the ground with pincers resting still either flat or poised at the midway mark. Its final position is the tiptoe position with its body angled and lifted off the ground and in the air, pincers still folded but held off the ground with its walking legs fully extended. [1]
C. lavauxi are usually found under stones, with their hind legs grasping stones which pushes the back half of the crab up onto the stone clasping it with its talons with the crab using its other legs to support its weight. This is in order to increase its mobility and stabilize the crab against the effects of tidal action. [1] They also use their pincers and talons to dig burrows and push stones away. These holes have been found to be between 20 and 40 mm deep under the cover of rock. [1] Further, C. lavauxi can make clicking noises with the sound acting as a sort of distant artillery. [1] It is one of the only crabs in New Zealand that can perform such an action.
C. lavauxi has evolved to become a versatile and robust species that is able to cope in extreme conditions that many species of crab in New Zealand cannot. This has resulted in an overall greater abundance and success in its population, leading it to be one of New Zealand's most common crabs.
The New Zealand pea crab, is a species of small, parasitic crab that lives most commonly inside New Zealand green-lipped mussels. Adult females are about the size and shape of a pea, while adult males are smaller and flatter. Adult New Zealand pea crabs are completely reliant on their host mussel for shelter and food, which it steals from the mussel's gills. The New Zealand pea crab is found throughout New Zealand and can infect up to 70% of natural populations. These crabs are of concern to green-lipped mussel aquaculture because they reduce the size and growth of mussels, although infected mussels can be harvested and consumed.
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.
Hemigrapsus sexdentatus, also called the “common rock crab” or “common shore crab,” is a marine crab indigenous to the southern shores of New Zealand. This crab is a member of the Varunidae family in the order Decapoda.
Hemigrapsus crenulatus, the hairy-handed crab or papaka huruhuru, is a marine crab of the family Varunidae, endemic to the New Zealand coast, although a taxon in Chile may be conspecific. It is an intertidal species with semi-terrestrial tendencies. They are named by their characteristic setae, or patches of thick hair, on the chelipeds and legs. They can range from green to brown in coloration. Adult crabs are generally 2–4 cm (0.8–1.6 in) wide at the carapace, although the smallest mature crabs can be around just 1 cm (0.4 in) wide. and are able to survive and reproduce in environments of widely varying salinities.
Leptograpsus variegatus, known as the purple rock crab, is a marine large-eyed crab of the family Grapsidae, found in southern subtropical Indo-Pacific Oceans. It grows to around 50 millimetres (2.0 in) shell width. It is the only species in the genus Leptograpsus.
Petrolisthes elongatus, known as the New Zealand half crab, elongated porcelain crab, blue half crab, blue false crab or simply as the half crab or false crab, is a species of porcelain crab native to New Zealand.
Ovalipes catharus, commonly known as the paddle crab, swimming crab, or, in Māori, pāpaka, is a species of crab in the family Ovalipidae. It is found in shallow, sandy-bottomed waters around the coasts of New Zealand, the Chatham Islands, and uncommonly in southern Australia. O. catharus is an opportunistic, aggressive, and versatile feeder active mostly at night, preying predominantly on molluscs and crustaceans. It is also highly prone to cannibalism, which accounts for over a quarter of its diet in some locations. The crab's paddle-shaped rear legs and streamlined carapace allow it to swim rapidly to capture prey and to burrow in the sand in order to escape predation. Its mating season is in winter and spring; the male carries the female until she moults, after which the two mate and the female likely moves into deeper waters to incubate and disperse her larvae.
Notomithrax ursus, known as the hairy seaweed crab, is a spider crab of the family Majidae.
The oyster crab is a small, whitish or translucent crab in the family Pinnotheridae.
Latreilliidae is a small family of crabs. They are relatively small, long-legged crabs found on soft bottoms at depths of up 700 metres (2,300 ft) in mostly tropical and subtemperate waters around the world. Their carapace is very small and doesn’t cover the bases of their legs, which protrude from the cephalothorax in a spider-like manner. The family and its type genus are named after Pierre André Latreille. The oldest known fossils from the Latreillidae have been dated to the middle of the Cretaceous period. It comprises seven extant species.
Hemigrapsus oregonensis is a small shore crab of the family Varunidae; formerly classified under the family Grapsidae. It is known under several common names, including yellow shore crab, hairy shore crab, green shore crab, mud-flat crab, bay shore crab and Oregon shore crab. Despite its common name, the crab actually has a wide variety of coloration. It is found along the West Coast of the United States and Canada, specifically along shorelines and similar geographical areas. In 2009, H. oregonensis was included on a list of animals petitioning for the endangered species label, but there was not enough scientific information available for it to be considered as such, so it remains unevaluated to the present day.
Minuca pugnax, commonly known as the Atlantic marsh fiddler crab, is a species of fiddler crab that lives on north-western shores of the Atlantic Ocean.
Ocypode gaudichaudii, also known as the painted ghost crab or cart driver crab, is a species of crab found on Pacific beaches from El Salvador to Chile as well as on the Galápagos Islands. The species was first described by Henri Milne-Edwards and Hippolyte Lucas in 1843.
Tumidodromia dormia, the sleepy sponge crab or common sponge crab, is the largest species of sponge crab and the only species in the genus Tumidodromia. It grows to a carapace width of 20 cm (8 in) and lives in shallow waters across the Indo-Pacific region.
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.
Cancer johngarthi is a species of crab that lives in the eastern Pacific Ocean from Mexico to Panama. It was separated from C. porteri in 1989, and is the subject of a small-scale fishery off Baja California.
Mictyris guinotae is a species of soldier crab of genus Mictyris, endemic to the Ryukyu Islands of Japan. They were named after Danièle Guinot, a professor at the Muséum national d'histoire naturelle in France, and were first treated as a separate species in a tribute volume to Guinot.
Macropodia rostrata, common names, the common spider crab, long-legged spider crab, long-legged crab, is a species of marine crab in the family Inachidae. The Macropodia Rostrata visually mimics many other types of small crabs with the exception of its long legs. By attaching algae to their thin legs, they can be confused with the stem of seaweed. This is both a defense mechanism and a predatory advantage, as unsuspecting fish will hide in seaweed beds from nearby predators. This behavior can be absent among larger crabs, and those that live at great depths like giant Japanese spider crabs.
Armases cinereum, also known as the squareback marsh crab or wharf crab, is a species of crab in the family Sesarmidae. The wharf crab is a small crab that is dark brown to muddy in color, which allows it to blend in with its usual surroundings. It is found on the Atlantic southeastern coast, down into the Gulf of Mexico. It is an omnivore and is prevalent in marshy coastal environments along the Southwestern Atlantic.
