Red rock crabs can be found along coasts of subtropical and tropical North America, South America, and the islands occuring within this range in both the Pacific and Atlantic Oceans. They are most commonly found in coastal areas of Baja, California, from Mexico to Peru, Ecuador, the Caribbean, Brazil, Florida, and the Galapagos Islands. (Alonso, 2012; Davis, 2004)
Adult red rock crabs live along rocky shorelines, usually at or above the spray line in tropical and subtropical North America, South America, and islands occuring around this latitude in both the Pacific and Atlantic oceans. When it comes time for eggs, carried by females, to hatch, females go to a calm shallow area so larvae can drop straight into the water. Red rock crab larvae are free swimming in shallow waters just off-shore. After they metamorphose, juveniles makes their way back to rocks on the shore, their primary habitat. (Weisz, 2012)
- Aquatic Biomes
- Other Habitat Features
- intertidal or littoral
- Range elevation
- 0 to 5 m
- 0.00 to 16.40 ft
- Average elevation
- 1 m
- 3.28 ft
Red rock crabs are vividly multi-colored. Adults are typically bright yellow and red with black stripes around the edges of their carapaces and black or green dots near their eyes. Leg joints are often black or a dark green color, each leg ending with a bright orange or yellow tip, and claws are typically bright red. Their underbellies are usually pale white. These crabs are typically darker in color as young adults, growing brighter with age. Carapaces range in size from 5-8 cm in width. They have four large segmented walking legs with spine-like projections near the tip of each leg, and two arms with pinchers. They have two eyes on short stalks at the fronts of their bodies. Males tend to be slightly smaller than females, and their right claws are slightly larger than their left claws. ("Sally Lightfoot", 1978; Freire, et al., 2011; Guerao, et al., 2011; Mejia, 1995; Snow, 1998; Warner, 1977)
Larvae (zoea) are about 0.5 mm long and have smooth bodies with long spines and a slender, curved abdomen ending in a forked telson. Their abdomens have five somites, eight legs, two arms with minimal claws and sessile eyes. They have four antennae on their heads. ("Sally Lightfoot", 1978; Guerao, et al., 2011; Warner, 1977)
- Sexual Dimorphism
- female larger
- sexes shaped differently
- Range length
- 5 to 8 cm
- 1.97 to 3.15 in
Females carry their eggs under their bodies until they hatch, when they help to release larvae from eggs by using their chelae to disturb their egg mass and wave their bodies in shallow water. After hatching, larvae swim out to deeper waters where they consume phytoplankton and undergo a series of quick molts. More body segments are added after each molt, and two appendages, used for swimming, are added to each new segment. Eventually (an exact number of molts is not known) larvae undergo metamorphosis, becoming juveniles. Juveniles are similar in appearance to adults but are smaller and darker, usually dark green or black with dark red limbs. Juveniles make their way back to rocky shorelines, where they feed as adults and continue to grow by molting, achieving greater size and brighter coloration with each molt. After this puberty molt, the chelae of males grow quickly and females' abdomens become larger in preparation to hold eggs. Adults grow throughout their lives, with longer periods of time between each molt as they age. This species can regenerate lost limbs. ("Sally Lightfoot", 1978; Davis, 2004; Freire, et al., 2011; Guerao, et al., 2011; Warner, 1977)
During courtship, males will battle for females by first facing each other then side stepping right and left in tandem while touching claws. If neither crab retreats, one crab will lunge at the other and try to grab his rival's claws and break them off; if this occurs, the retreating crab is chased away by the victor, who now has access to a nearby female. This male deposits his sperm into the spermathecae of athe female; the release of sperm is aided by secretions from gonopod tegumental glands, which lubricate the narrow ejaculatory canal and thin out the ejaculate. After receiving sperm, females release their fertilized eggs, storing remaining sperm in their spermathecae. Eggs remain suspended on a female's belly for protection until hatching. Females will only mate again when all stored sperm has been used, which is dependent on how many eggs are produced at a time. While females will only mate with one male at a time, males and females may have multiple partners over a breeding season. ("Sally Lightfoot", 1978; Beninger and Larocque, 1998; Davis, 2004; Freire, et al., 2011)
- Mating System
- polygynandrous (promiscuous)
Breeding occurs year round, particularly in more tropical ranges, but egg hatching seems to coincide with full moons. Males mate often but must wait 10-20 days to regenerate sperm. Females mate less often than males, only when stored sperm has been depleted; depletion time depends on how many eggs are produced, anywhere from 20-100 per clutch, which is dependent on resource abundance and female size. Females molt shortly following hatching a clutch of eggs and will lay eggs again soon after, typically every 24 days. Females carry eggs on their underbellies. Eggs may take up to three weeks to hatch, at which time embryos are aided in hatching by females. Exact age at sexual maturity is unknown, although a puberty molt has been noted at a carapace length of 51.4 mm for males and 33.8 mm for females. After mating, males and females return to their solitary lifestyles. (Davis, 2004; Freire, et al., 2011; Hartnoll, 2009; Warner, 1977)
- Key Reproductive Features
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- delayed fertilization
- Breeding interval
- Sally Lightfoot crabs may breed multiple times throughout the year.
- Breeding season
- Breeding season for this species is year-round.
- Range number of offspring
- 20 to 100
- Average gestation period
- 3 weeks
Male red rock crabs exhibit no parental involvement following fertilization. Females carry fertilized eggs underneath their bodies to protect them from predators and keep them out of direct sunlight. Ocean spray and water from females' bodies keep her eggs moist. When it is time for eggs to hatch, females aid this process by rubbing them between their bodies and a rough surface, over shallow water. Larvae drop into the water and are completely independent. ("Sally Lightfoot", 1978; Davis, 2004; Warner, 1977)
- Parental Investment
- female parental care
Red rock crabs are known to live for up to 10 years in captivity. Average lifespan in the wild is unknown and limited mainly by predation. (Freire, et al., 2011)
- Range lifespan
- 10 (high) years
- Range lifespan
- Typical lifespan
- 5 to 10 years
- Typical lifespan
- Average lifespan
- 7 years
- Average lifespan
The larvae of this species are free swimming; it is unknown whether they stay in groups and what their strategies may be for protection from predation. Juveniles typically live in groups, while adult crabs live solitary lives, only coming together around food sources or for mating; there is no notable interaction between individuals otherwise, even when they encounter each other. These crabs are typically most active during morning and afternoon, when they search rocks in coastal zones for food or mates. This timing reduces exposure to predators and prevents dessication during times of high heat. They move very quickly and with great agility, and can cling tightly to rocks when hit by surf while feeding. When not out searching for food and mates, red rock crabs spend their time in the cracks of rocks or other shaded, small areas into which they can deeply wedge themselves for protection from predators. If this fails to protect them, they may spit a stream of water at a predator, use their claws for protection, or even shed a leg, which can be grown back. (Davis, 2004; Freire, et al., 2011; Gianuca and Vooren, 2007; Raymond and Fenner, 1990)
Individuals do not have selected territories, tending to wander about rocky shorelines looking for food and mates before returning to nonspecific rock outcroppings. ("Sally Lightfoot", 1978; Freire, et al., 2011)
Communication and Perception
These crabs communicate using touch, chemical signals, and visual cues. Antennae are used by larvae as tactile receptors. Adults have fine spine-like projections near the tip of each leg, which are used for chemoreception (pheromones) as well as sensing vibration and other tactile input. This species has compound eyes and use their acute vision to find prey. ("Sally Lightfoot", 1978; Davis, 2004; Mejia, 1995)
- Other Communication Modes
Red rock crabs feed on sponges, mollusks, crustaceans, fishes, carrion (mainly seals and birds), young sea turtles, bird eggs and droppings, algae, and bat guano. As larvae, they feed on phytoplankton. Most food is obtained by scavenging along rocks and the shoreline. Live fish may be caught in shallow waters with their claws and mollusks, such as clams, may be found during low tides. These crabs are known to feed on ticks that they remove from live marine iguanas. They have been known to resort to cannibalism when populations densities are high or food is scarce. Red rock crabs use their claws to scrape food off rocks or capture live animals as well as to move the food into their mouths, and can break open tough material like mollusk and crab shells or corals that may wash ashore. ("Sally Lightfoot", 1978; Gianuca and Vooren, 2007; Snow, 1998; Weisz, 2012)
- Primary Diet
- Animal Foods
- terrestrial non-insect arthropods
- aquatic crustaceans
- other marine invertebrates
- Plant Foods
- Other Foods
These crabs have many predators including a variety of birds, octopuses, eels, fishes, and cats. They try to avoid predation by moving quickly and hiding in rock crevices during daytime hours. When cornered, they will shoot a stream of water to scare a predator away, pinch with their claws, or drop a leg in order to escape. They rely on their thick carapaces for defense. (Chave and Randall, 1971; Davis, 2004; Koneeny, 1987; Sazima and Bastos de Almeida, 2009; Vaske, et al., 2003; Warner, 1977; Weisz, 2012)
- Known Predators
- Brown Booby (Sula leucogaster)
- Galapagos lava heron (Butorides striata sundevalli)
- House cat (Felis catus)
- Octopus (Class Cephalopoda, Phylum Mollusca)
- Wahoo (Acanthocybium solandri)
- Yellowfin Tuna (Thunnus albacares)
- Little banded eel (Echidna catenata)
- Moray Eel (Gymnothorax pictus)
- Kemp's ridley sea turtle (Lepidochelys kempii)
Red rock crabs feed on dead animals and algae, cleaning up beaches and rocks along coastlines. They help control some bird populations by eating their eggs. They also provide a source of food for many animals that live along coastlines. ("Sally Lightfoot", 1978; Warner, 1977)
These crabs have been known to pick ticks from marine iguanas, suggesting a mutually beneficial relationship between these species. (Weisz, 2012)
Red rock crabs are hosts to a number of parasites, including isopods. (Markham, 2002)
- Ecosystem Impact
- Marine iguana (Amblyrhynchus cristatus)
- Lobocepon sp. (Family Bopyridae, Order Isopoda)
Economic Importance for Humans: Positive
Red rock crabs are used, alive or dead, as bait for shoreline fishing. They also help maintain clean shorelines, which is particularly important in areas that rely on tourism. They are sometimes available in the pet trade. (Snow, 1998)
Economic Importance for Humans: Negative
If bothered, these crabs may give a painful pinch or squirt water on their antagonizers. Other than these very minor, avoidable problems, this species presents no adverse effects to humans. (Snow, 1998)
- Negative Impacts
- injures humans
This species has not been evaluated by IUCN and is not currently considered endangered or threatened. (IUCN, 2012)
Nick Miller (author), University of Michigan-Ann Arbor, Jeremy Wright (editor), University of Michigan-Ann Arbor.
- Atlantic Ocean
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
- Pacific Ocean
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
helps break down and decompose dead plants and/or animals
an animal that mainly eats meat
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
an animal that mainly eats the dung of other animals
active at dawn and dusk
- delayed fertilization
a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.
an animal that mainly eats decomposed plants and/or animals
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
- active during the day, 2. lasting for one day.
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- female parental care
parental care is carried out by females
union of egg and spermatozoan
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- indeterminate growth
Animals with indeterminate growth continue to grow throughout their lives.
- internal fertilization
fertilization takes place within the female's body
- intertidal or littoral
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
- oceanic islands
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- pet trade
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats fish
an animal that mainly eats plankton
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- saltwater or marine
mainly lives in oceans, seas, or other bodies of salt water.
an animal that mainly eats dead animals
reproduction that includes combining the genetic contribution of two individuals, a male and a female
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
- year-round breeding
breeding takes place throughout the year
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