Speckled Swimming Crab
Arenaeus cribrarius
Distribution 5
Virginian, southside of Cape Cod to Cape Hatteras
Physical description 6
The carapace of speckled swimming crabs is twice as wide as it is long and can be as wide as 154 mm. The carapace ranges in color from light reddish brown to olive brown and is covered with many small, rounded white spots. The chelipeds (claws) are short and narrow. They have 4 pairs of short, broad pereopods (walking legs) with yellow tips. The fifth pair of pereopods is flattened and paddle-shaped. The perepods and the lower surface of the carapace are densely covered with hair. Speckled swimming crabs can weigh as much as 45 g.
Range mass: 45 (high) g.
Range length: Carapace width 154 (high) mm.
Other Physical Features: heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently; male more colorful
Habitat 7
Speckled swimming crabs live along sandy beaches in shallow to deep water up to 68 m in depth. They have been found in waters 11 to 28.6 °C in temperature and 27.5 to 35 PSU in salinity. When on land, they prefer the foreshore area of beaches in fine mixed sands with low organic matter.
Range depth: 0 to 68 m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: benthic ; coastal
Communication and perception 8
As with other crustaceans, speckled swimming crabs communicate through visual, acoustic, chemical and tactile cues. The associated senses are also used in perceiving the environment.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Development 9
Speckled swimming crabs have 4 main stages of life; they begin as planktonic zoea, become megalops, benthic juveniles, and finally adults. Speckled swimming crabs pass through 8 stages as zoea, each lasting 4 to 6 days. After each stage, they molt and develop into the next stage of zoea. The body of zoea primarily consists of the head. They have a single dorsal spine in the middle of the head and a long rostrum extending downward beneath the eyes. Zoea also have a long abdomen. Megalops resemble a tiny lobster. During this stage, the head slightly elongates, the dorsal spine, located posterior to the head, shortens, they eyes become stalked, and small chelipeds develop. The abdomen remains long and has now developed prominent peropods. After 13 days, megalops metamorphose into a juvenile crab, with a prominent carapace with two lateral spines projecting from the outer edges. Juveniles have larger chelipeds and a flattened pair of 5th peropods. If juveniles successfully survive, they eventually become adult crabs.
Development - Life Cycle: metamorphosis ; indeterminate growth
Reproduction 10
Between molting periods, male speckled swimming crabs express a courtship display to attract premolted females. The display intensifies when a potential mate is visually recognized. After a female is chosen, the male grasps the female with his chelipeds and holds her under himself for 25 to 35 days until the female molts. Soon after the female molts, when her shell is still soft, the male inverts her so they are positioned abdomen to abdomen. He penetrates her with specially-modified pleopods, transferring spermatophore packages into her gonopores. After copulation, he continues to carry her for 24 to 36 days until her shell has hardened completely. Speckled swimming crabs are polygynandrous, meaning males and females have multiple mates.
Mating System: polygynandrous (promiscuous)
Speckled swimming crabs breed year-round, although breeding is more common in the summer and winter, when water temperature oscillations are reduced. Females can produce between 135,000 and 682,000 eggs. Like other members of the family Portunidae, speckled swimming crabs communicate during the reproductive period, which can occur through visual, acoustic, chemical and tactile cues. Speckled swimming crabs reach sexual maturity when their carapace is between 60 and 64 mm in width, which generally occurs around 60 to 80 days of age.
Breeding season: Speckled swimming crabs breed year-round, but breeding is more common in summer and winter.
Range number of offspring: 135,000 to 682,000.
Range age at sexual or reproductive maturity (female): 60 to 80 days.
Range age at sexual or reproductive maturity (male): 60 to 80 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
After copulation, female speckled swimming crabs extrude fertilized eggs and carry the egg mass beneath her abdomen with specially-modified pleopods. Females protect their egg mass and fan it with their pleopods to oxygenate the developing eggs and keep them clean. After larvae hatch and are released into the water column, there is no further parental care.
Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female)
Link to Access Genomic Data 11
http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=375456&lvl=0
Sources and Credits
- (c) Jose Nunez, some rights reserved (CC BY-NC-ND), uploaded by Jose Nunez
- (c) matbio, all rights reserved
- (c) Rusty, some rights reserved (CC BY), uploaded by Rusty
- (c) Patrick Coin, some rights reserved (CC BY-NC-SA), http://farm3.static.flickr.com/2026/2340834424_d0a86a9029.jpg
- (c) WoRMS for SMEBD, some rights reserved (CC BY), http://eol.org/data_objects/28470519
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18634254
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18634253
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18634258
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18634255
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18634256
- (c) Emily Rose Sharkey, all rights reserved
