Cancer irroratus (Essay Sample)

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Cancer irroratus
Introduction
The common name for Cancer irroratus is Atlantic rock crab. It belongs to the kingdom animalia, class Malacostraca, order Decapoda, family Cancridae, genus Cancer and species Cancer Irroratus (MacKenzie, & John, 2005).
Habitat and behavior
This species inhabits the Atlantic ocean, where they are highly concentrated in the eastern coast of North America. Their native habitat is the benthic regions of the ocean. However, they are also capable of adapting to different variations of depth of the ocean. They are able to exist in deep water of up to 2,600 feet to very shallow waters, with temperatures of between 75 to 85 degrees Fahrenheit (Stanley, 2005). They prefer living in the substrates that have rocks or loose materials. The small crabs that have the width of cephalorthorax, 50 mm, prefer living in at the bottom of mud or sand while the large crabs prefer rock bottoms.
Since their main habitat is the benthic zones of the ocean which could range from shallow up to 2,600 feet, there is limited food for them that can survive at such conditions. This makes them opportunistic feeders (Jones, 2003). This means that they only eat food when it is available. Some of the things that they eat are algae, some polychaetes, some mussels, gastropods, among several crustaceans such as hermit crabs. It is interesting to note that Cancer irroratus are highly responsive and have a high affinity to the foods that they are accustomed to unlike to the foods that they are not familiar with (Hinton, 1995). When they feed on some specific species, they are capable of noticing the different orders that are exhibited by these species. They will then begin to develop a preference in the species that they are familiar with. It is also for this reason that these crabs are able to detect the odors of their prey (Rogers, 1999).
Since they are usually scavengers, the Cancer irroratus usually are very mobile, and do not prefer remaining in one specific place for a long period of time. During the autumn, their preferred period of reproduction, crabs will often prefer to remain in the shallow waters where they strategically burry themselves in rocks or tide pools to keep away from predators. Their main predator is the lobster which usually feed on the larva or Megalops (Ingle, 1997). When they are at maturity size, rock crabs are usually safe from the lobsters – although some of them are eaten when they attempt to steal bait from the pots of lobsters and get captured by the same (Research Publications of the National Biological Service, 1995).
Reproduction
The reproduction of Cancer irroratus takes place during autumn. Females attain sexual maturity at a CW size of 60 millimeters. On the other side, males have a slightly bigger CW size of 70 millimeters at their sexual maturity. Before mating can commence, the males and females will first have to moult their shells. This usually happens, for males, during the winter period to ensure that the shells are completely firm when they are falling. The females will moult their shells when the fall is taking place so that they are soft during the mating period (Drew, 2010). Rock crab shells take up between 2 to 3 months to become hard. After fertilization takes place, the female crabs will lay eggs which they store inside their stomachs for up to one year. Depending on the size of the female crab, the number of eggs that the female crab produces is between 125,000 and 500,000. After this duration of time, the eggs will hatch but the larva will stay on the on the column of water for the months between June up to September. When it reaches autumn again, the larva that has hatched will metamorphose to become small crabs that are known as Megalops. Since at the beginning of their lives these young crabs are very vulnerable to predators and big turbulence in the water, they will either stay in shallow waters or deep on the floor of the ocean where there is adequate protection so as to increase their chances of surviving (Leet, 2001).
Relationship with humans
Fishing of rock crabs was first done in the year 1970, and has taken considerably a long time to grow (Robichaud, 2000). This makes it a considerably new idea, bearing in mind fishing or other species begun decades ago. New markets for rock crabs have developed - something that has led to an increase in the number of sea crabs fished. This led to regulations being set up by the Department of Fisheries and Oceans in an attempt to ensure that the species survives. Some of these regulations are introduction of licenses that would allow for fishing, fishermen were not allowed to fish female rock crabs, and fishermen were only required to fist crabs with a CW size of 102 millimeters (Fishery Bulletin, 2001). These measures were put up to ensure that reproduction of rock crabs would be high. This is one industry that has shown great potential since more and more markets are coming up. However, some people have come up to criticize fishing of rock crabs since they are known to be very important food for lobster (Richards, 1999). The lobsters depend on the small rock crabs, their larva, and those that are trapped in the lobster pots for food. It is for this reason that increased fishing of rock crabs will affect negatively the population and existence of lobsters (Vernberg, 2002).