Cyclograpsus lavauxi
 | This article's tone or style may not reflect the encyclopedic tone used on Wikipedia. (July 2018) |
| Cyclograpsus lavauxi | |
|---|---|
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| 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]
Description
Cyclograpsus lavauxi is a small, temperate crab in the Grapsidae family.[2] The crab is roughly the size of a coin,[3] with the adult males averaging 28 mm and females averaging 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 antennas 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. Cyclograpsus spp. is agile and alert, resulting in a very mobile and versatile crab.[7]
C. lavauxi has been observed in a number of different colours. Their carapace can vary in colour 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 colour than the carapace.[1] The legs display the same colouring as the carapace with brighter speckled colouring.[4]
Distribution
Natural global range
The smooth shore crab's natural range is New Zealand and Chile in the Juan Fernandez Islands.[1][8]
New Zealand range
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]
Habitat preferences
C. lavauxi occurs in a multitude of habitats[9] including boulders, under stones and on beaches ranging from exposed coasts to sheltered bays.[1] It is a fairly common crab on New Zealand shores and typically outnumbers the larger common rock crab species.[1] It can be found near the littoral sea fringe where it is wetted only slightly or not at all.[10] It has also been found in intertidal levels, mudflats, estuaries and rocky shores.[11] Older individuals are often found higher on the foreshore or mudflats than younger individuals while younger crabs prefer the lower lines of the foreshore and mudflats. During the summer months, all C. lavauxi move down into the lower foreshore line.[2]
Life cycle/phenology
Reproduction
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]
Brockerhoff and McLay found that males approach a female and hold on to her carapace for an hour, after which there was a two hour long copulation.[13] Oftentimes female will resist males and try to escape.[13]
Females only carry eggs between November and February[14] and have a short reception time of less 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 was stored in the spermatheca after mating.[13] Females only lay eggs once per mating season.[12]
The eggs initially are a dark purple color after laying, but grow paler and have obvious 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]
Moulting
C. lavauxi tend to moult soon after the breeding season has ended, in late summer to early autumn.[13]
Diet and foraging
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]
Predators, parasites, and diseases
A number of species predate on C. lavauxi, particularly bird species due to the crabs' habiting the area where the tide does not often reach.[15] Their main predators are generalist birds such as Seagulls or Kingfisher.[9] Fish species including the Smooth Hound Fish, Spined Dogfish, Terakihi, Sea Perch, Moki and Red Gurnard also occurs.[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] Brockerhoff[18] found 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. Brockerhoff's study also suggests that females did not avoid either the unparasitized and parasitized males due to there being no visible disadvantages to either.[18]
Other features
C. lavauxi has the ability to live successfully under large amounts of sediment. Bacon[5] found that Cyclograpsus insularum was only able to tolerate 18% of sediment underneath boulders while C.lavauxi can withstand up to 63% of sediment. 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] Its major body postures include being flat with its pincers folded and lying on the ground with its walking legs close and side-by-side. When in a raised position it place 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.
References
- ^ a b c d e f g h i j k l m n McLay, C.L (1 January 1988). "Brachyura and crab-like anomura of New Zealand". Leigh Laboratory Bulletin (22): 310–316. hdl:2292/3450.
- ^ a b Little, C (1990). "The terrestrial invasion: An ecophysiological approach to the origins of land animals". Journal of Evolutionary Biology. 4 (4): 689. doi:10.1046/j.1420-9101.1991.4040689.x.
- ^ a b c d "Crab, Smooth Shore". Departement of Marine Science. Retrieved 2016-04-06.
- ^ a b c Wilkens, S.; Ahong, S. "Coastal crabs – a guide to the crabs in New Zealand" (PDF). NIWA.
- ^ a b c d e f Bacon, M.R. (1971). "Distribution and ecology of the crabs Cyclograpsus lavauxi and C. insularum in Northern New Zealand". New Zealand Journal of Marine and Freshwater Research. 5 (3–4): 415–426. doi:10.1080/00288330.1971.9515395.
- ^ Cuesta, J.A.; Diesel, R.; Schubart, C.D. (2001). "Re-examination of the zoeal morphology of chasmagnathus granulatus, Cyclograpsus lavauxi, Hemigrapsus sexdentatus, and H. crenulatus confirms consistent chaetotaxy in the varunidae (Decapoda, Brachyura". Crustaceana. 74 (9): 895–912. CiteSeerX 10.1.1.487.137. doi:10.1163/15685400152682656. JSTOR 20105326.
- ^ Hayward, John Morton ; scientific editor Bruce W. (2004). Seashore ecology of New Zealand and the Pacific. Auckland, N.Z.: Bateman. ISBN 978-1-86953-399-1.
{{cite book}}:|first1=has generic name (help)CS1 maint: multiple names: authors list (link) - ^ Griffin, D. J. G. (1 January 1968). "A New Species of Cyclograpsus (Decapoda, Grapsidae) and Notes on Five Others from the Pacific Ocean". Crustaceana. 15 (3): 235–248. doi:10.1163/156854068x00359. JSTOR 20103005.
- ^ a b c Marsden, I.D.; Dewa, R.S. (30 March 2010). "Diel and tidal activity patterns of the smooth shore crab (Milne Edwards 1853)". Journal of the Royal Society of New Zealand. 24 (4): 429–438. doi:10.1080/03014223.1994.9517478.
- ^ Innes, A.J.; Forster, M.E.; Jones, M.B.; Marsden, I.D.; Taylor, H.H. (September 1986). "Bimodal respiration, water balance and acid-base regulation in a high-shore crab, Cyclograpsus lavauxi H. Milne Edwards". Journal of Experimental Marine Biology and Ecology. 100 (1–3): 127–145. doi:10.1016/0022-0981(86)90159-0.
- ^ Dell, R. (1963). Native Crabs (Nature in New Zealand). Wellington, N.Z.: A.H & A. W. Reed. p. 56.
- ^ a b c d Wear, Robert G. (1970). "Life‐history studies on New Zealand Brachyura". New Zealand Journal of Marine and Freshwater Research. 4: 3–35. doi:10.1080/00288330.1970.9515324.
- ^ a b c d e f g h i j Brockerhoff, A.M.; McLay, C.L. (2005). "Comparative Analysis of the Mating Strategies in Grapsid Crabs with Special References to the Intertidal Crabs Cyclograpsus Lavauxi and Helice Crassa (Decapoda: Grapsidae) from New Zealand". Journal of Crustacean Biology. 25 (3): 507–520. doi:10.1651/c-2548.
- ^ a b c Taylor, H.H.; Leelapiyanart, N. (2001). "Oxygen Uptake by Embryos and Ovigerous Females of Two Intertidal Crabs, Heterozius rotundifrons (Belliidae) and Cyclograpsus lavauxi (Grapsidae): Scaling and the Metabolic Costs of Reproduction". The Journal of Experimental Biology. 204 (Pt 6): 1083–1097. PMID 11222127.
- ^ a b Hazlett, B.; Bach, C.; Thacker, R.; McLay, C. (2000). "A Comparative Study Of The Defense Syndromes Of Some New Zealand Marine Crustacea" (PDF). Crustaceana. 73 (8): 899–912. doi:10.1163/156854000504903. hdl:2027.42/43663. JSTOR 20106360.
- ^ Graham, D.H. (1939). "Food of the fishes of the Otago Harbour and adjacent sea" (PDF). Transactions and Proceedings of the Royal Society of New Zealand. 68: 421–436.
- ^ Koehler, A.; Poulin, R. (2010). "Host partitioning by parasites in an intertidal crustacean community". Journal of Parasitology. 96 (5): 862–868. doi:10.1645/GE-2460.1. PMID 20950092. S2CID 3940885.
- ^ a b c Brockerhoff, A.M. (2002). ). Comparative studies of the reproductive strategies of New Zealand grapsidae crabs (Brachyura: Grapsidae) and the effects of parasites on their reproductive success (Ph.D). University of Canterbury.
