C.guanhumi molts 60 times during its lifespan, compared to 20 times, which is typical of other crab species. After achieving sexual maturation, becomes primarily terrestrial, returning to the ocean only to spawn and begin the life cycle once again. (Burggren and McMahon, 1988)has a complex life cycle that begins during the rainy season (which varies by latitude) when females spawn their eggs into the ocean, strictly coinciding with the lunar cycle. Once hatched molts through five larval periods before it undergoes metamorphosis into a megalops, the stage when the appendages first appear. The nest metamorphosis produces the juvenile crab, which closely resembles the adult form. Each metamorphosis is accompanied by a molting of the cuticle. The following molt, named the puberty molt, precedes full sexual maturation. Molting regulates the life cycle of . Generally,
After fertilization, females carry their eggs on their backs for approximately two weeks. At this point, the eggs begin to hatch, and she shakes them off into the ocean. In spite of its evolution toward terrestriality, (Burggren and McMahon, 1988; Hill, 2001)is still heavily dependent on the ocean for at least part of the life.
Many giant land crabs do not survive the larval stage. Those who reach adulthood achieve sexual maturity in approximately four years. Unfortunately, there is not much further data available regarding the lifespan of (Burggren and McMahon, 1988). However, biologists hypothesize that the lifespan of a species of land crab is inversely proportional to its growth rate. In other words, the faster they grow, the shorter they live, and vice versa. From this, it is probable that has a relatively longer lifespan than other land crabs, as it grows more slowly and molts three times as much (averaging 60 molts per lifetime as opposed to 20). In fact, the largest female kept in captivity lived 13 years. Albeit biologists admonish against extrapolating laboratory findings to a species' actual environment, I have given some rough estimates of lifespan below based on given data regarding the lifespans of and other land crabs.
Due to their size, (Burggren and McMahon, 1988)is not heavily preyed on. However, it sometimes falls prey to large birds, mammals, and other . Humans are the largest threat with respect to predation, harvesting giant land crabs in massive quantities for food. Fortunately, it is fairly safe in its burrow from predation. Hence, burrowing not only provides with shelter, but also protects it from predation. In fact, the absence of a burrow, in addition to physical vulnerability and other factors, explains the high mortality rates of during the larval stage.
Due to the moist atmosphere within its burrow, (Burggren and McMahon, 1988)provides a myriad of arthropods with habitats. These arthropods live on its body, but do not seem to harm it, primarily feeding off of left over debris from previous meals. Because the food habits of are so eclectic, its effect on its prey populations are, if anything, trivial. However, through preferential feeding, can alter the compositions of various species of plants by choosing to eat certain plants and seeds over others.
Although ("Blue Land Crabs Draft Rule Review", 2002)is not endangered, there is concern regarding its harvesting. It has been exploited excessively in the Caribbean for food. To combat this, Puerto Rico enacted strict regulations and Florida is currently considering similar legislation.
Renee Sherman Mulcrone (editor).
Samuel Wedes (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.
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.
uses sound to communicate
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.
flesh of dead animals.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
active at dawn and dusk
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
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.
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.
having the capacity to move from one place to another.
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.
chemicals released into air or water that are detected by and responded to by other animals of the same species
light waves that are oriented in particular direction. For example, light reflected off of water has waves vibrating horizontally. Some animals, such as bees, can detect which way light is polarized and use that information. People cannot, unless they use special equipment.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
Living on the ground.
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
Blue Land Crabs Draft Rule Review. Tallahassee, FL: Division of Marine Fisheries. 2002. Accessed 03/19/03 at http://www.floridaconservation.org/commission/2002/nov/LANDCRABDRAFTRULEREVIEW.pdf.
Burggren, W., B. McMahon. 1988. Biology of the Land Crabs. New York: Cambridge University Press.
Burggren, W., G. Moreira, M. Santos. 1993. Specific dynamic action and the metabolism of the brachyuran land crabs Ocypode quadrata (Fabricius, 1787), Goniopsis cruentata (Latreille, 1803) and Cardisoma guanhumi (Latreille, 1825). Journal of Experimental Marine Biology and Ecology, 169: 117-130.
Hill, K. 2001. "Cardisoma guanhumi" (On-line). Accessed December 04, 2004 at http://www.sms.si.edu/IRLSpec/Cardis_guanhu.htm.
Lloyd, R. 2001. "The Illusive Great Land Crab" (On-line). Accessed December 04, 2004 at http://www.mhhe.com/biosci/pae/marinebiology/casestudies/case_01.mhtml.
Pinder, A., A. Smits. 1993. The Burrow Microhabitat of the Land Crab Cardisoma guanhumi: Respiratory/Ionic Conditions and Physiological Responses of Crabs to Hypercapnia. Physiological Zoology, 66/2: 216-236.
anonymous, 2003. "Great Land Crab" (On-line). eNature.com. Accessed December 04, 2004 at http://www.enature.com/fieldguide/showSpeciesSH.asp?curGroupID=8&shapeID=1063&curPageNum=6&recnum=SC0010.