Blue crab
From CreationWiki, the encyclopedia of creation science
| Blue crab |
|---|
|
| Scientific Classification |
|
| Binomial Name |
|
Callinectes sapidus |
The Blue Crab is a species of crab located in the Atlantic Ocean from Argentina to Nova Scotia. The exoskeleton of the Blue Crab is very hard like most crustacean. They have claws for hunting and defensive purposes. Also walking and swimming legs for escaping from predators. The Female Blue Crab only mates once in its entire life, unlike its male counterpart. After releasing urine full of pheromones she will find a male partner to collect a sperm packet until she can borrow fertilized eggs into mud by a shore. Then she will carry them on her underbelly in a sponge until they emerge. The Blue crabs are used to make large profits in their harvest by commercial fisherman. They also have many different types of names like Jimmy, Sally, Sook, and Sponge Crab.
Contents |
Anatomy
The outside of the crab is called the exoskeleton which is very hard. If the crab is looking for food or trying to escape from a predator they can use their swimming legs which are two paddle like legs that are located on the back. The blue crab like most crustaceans have a defense system which are their claws that are also used for catching their prey.This crab sees through their eyes which are located in these talks that protect the eye. They also use antennae that find vibrations and chemical changes into water. The blue crab has to shed its shell which is called molting instead of growing. Although the outside of the crab is very hard, the inside of the crab is very soft. The crab had gills that takes oxygen into the blood stream that is pumped by the heart. The blue crab also had a stomach that can digest the food. All the cracks and curves that the crab has are filled with muscles that move their claws, swimming and walking legs. To find if a blue crab is male or female you would look at the under belly of it. The male blue crab has a long broom handle shape on the underbelly, while the female blue crab has a ball with a small point on its underbelly. [1]
Reproduction
Unlike the male blue crab, the female blue crab only mate once in their entire life. To become sexually mature, the females need to go through a pubertal molt and in that process they let out urine into the sea that has pheromones in it to attract the male blue crabs. The male crabs will perform something called cradle carrying which involves protecting the females by carrying them until the molt is over. At that point the females shell is soft and the male and female will then mate. The female will take and store one of the sperm sacks from the male crab and fertilize her eggs later. When all the mating is over the female crab goes to find a place where she can fertilize her eggs. The female blue crabs prefer spawning places are on the shore spawning areas and she will lay them in mud where she will carry them there. After mating the female will usually lay her eggs two to nine months after mating. The female will take her fertilized eggs and put them in a large sponge like object and keeps it on her underbelly until the babies emerge. The sponge usually takes two hours to make and often contains two million eggs. [2]
Ecology
Blue crabs are large predators in the bays of North America. The blue crab has life cycles that have very large migratory patterns which are very complex. Their life stages keep changing along many different habitats. The blue crab is also very important to many commercial fisherman. The blue crab is found on the western edge of the Atlantic Ocean from Argentina to Nova Scotia. They have found them in the waters of Japan and Europe. The blue crab have a large variety of predators like eels, drum, spot, trout, some types of sharks, and cownose sting rays. The blue crab is an omnivore, which means it eats both plants and animals. Blue crabs eat thin shelled annelids, bivalves, small fish, some plants and basically anything else they can find to eat, including carrion. The Chesapeake Bay, in Maryland and Virginia is known for their blue crabs because they get so much economic growth from harvesting the blue crabs. They got over one hundred million dollars from collecting blue crabs in the year of 1993. Since then the harvest for blue crabs have not been that good because the money from blue crabs was only 45 million dollars in the year of 2000. [3]
Blue Crab Names
There are many different types of names for the blue crab when they are in different stages of life and there different sex. One of the names for a blue crab is the Jimmy which is referred to a male crab because of its T shape on its under belly and it also has blue on the tips of their claws. The male Blue crab is much more difficult to determine if they are more immature or mature than the female Blue crab because the only difference with the male is that the underbelly is slightly thinner and inward than its mature version. Another name for Blue Crab is a Sally which is used to describe an immature female crab. They are only referred to as a Sally to watermen for a shorter way to say she crab. Also the immature female has its underbelly tighter and unable to open because it can not yet have eggs. For an adult female Blue Crab the name is a Sook. The Sook has a upside down U on its under belly and is more open because it is able to carry eggs. The last name is the Sponge crab which is use to talk about a female Blue Crab when it has its fertilized eggs stored in its sponge like attachment. [4]
Gallery
 |
 Blue Crab |
 Blue Crab |
 Browse |
References
- http://www.serc.si.edu/education/resources/bluecrab/anatomy.jsp
- http://www.bluecrab.info/lifecycle.html
- http://en.wikipedia.org/wiki/Blue_crab
- http://www.bluecrab.info/identification.html
| |||||||||||
