Callinectes Sapidus

(The Atlantic Blue Crab)

Nyasia Waddell

Introduction

The Callinectes sapidus, better known as the blue crab plays a huge role in the economy here on the east coast. The blue crab can be found in estuaries from Nova Scotia, through the Gulf of Mexico, and even as far as Uruguay. The blue crab gets its name mostly from the color of its claws and their outer shell. The rest of its body is like an olive green color. There is also a way to tell the difference between the male and the female crab. If you look at the underside of the crab, the each have what is called an apron. The apron on the female is more triangular shaped or round, and the males apron is like an upside down "T."

Scientific Classification

Scientific Name: Callinectes Sapidus

Common Name: The Blue Crab

The name Callinectes Sapidus actually means "beautiful swimmers." Over time, the blue crab developed hind legs that resembled the shape of a paddle, which allowed them to swim faster. The blue crab is also closely related to both the lobster and the shrimp.

Kingdom: Animalia

Phylum: Arthropoda

Class: Malacostraca

Order: Decapoda

Family: Portunidae

Genus: Callinectes

Species: Sapidus

Niche and Habitat

The blue crabs are bottom dwellers, and can be found in a variety of habitats. They can be found in the saltiest waters of the gulf to almost the freshest waters of the back bays. The natural habitat of the blue crab ranges from the Western parts of the Atlantic Ocean from Nova Scotia to Argentina. Although it is native to these places, they were introduced to other parts of the world, such as Asia, Europe, Hawaii and Japan. The females are found in areas of the estuaries with the highest salinity, especially when they are laying eggs. When the temperature gets colder, the crabs will migrate deeper into the water.

Evolutionary History

Overtime, the blue crab developed some adaptions due to natural selection. They developed sharper claws to help them tear into food easier. They developed a protein shell, which made their body lighter, allowing them to move faster. Another development that they had was an open circulatory system which allows nutrients to go directly to their tissues.

As far as the development of crab fishery goes, Native Americans and European settlers in the Chesapeake Bay area were eating crabs as early as the 1600s. It wasn't until the 1700s that the softshell and hard shell crab began to gain some type of value. Along the Atlantic coast, fisherman use to think that crabs were a nuisance because they would clog their nets and eat their bait. However, when they began to make a profit off of crabs, regulations had to be put in to place due to over harvesting. The fishing commissions of Virginia and Maryland implemented regulations in 1912 and 1917,

Environmental Impacts

In the food chain, the blue crabs is both a predator and prey. In the ecosystem, they are host to many parasites that don't harm them in any way. Barnacles, worms and leeches attach themselves to their outer shells; isopods are small animals that live in the gills or on the crabs abdomen; and they have small worms that can live in their muscles.

When crabs are being overharvested, it can cause problems in the ecosystem. Crabs prey on things like clams, oysters, and mussels. When the crab population declines, these populations would increase and can have a negative affect on the habitats environment. The decline in the blue crab population can also affect the fish and birds that use them as a food source.

Conservation

The blue crab has not been listed as an endangered species on anyone's list. However, they are sometimes overharvested by humans. Overharvesting of crabs can cause a disruption in the ecosystem.

Friends or Foes?

The blue crab is preyed on by the red drum, Atlantic croaker, hereon, sea turtles, and humans. Humans go crabbing and use crabs as a source of income. As listed above, the crab is a home to parasites such as barnacles, leeches, worms, and isopods.

Humans are probably the greatest foe of the blue crab. Specifically in the Chesapeake Bay area. Beginning in the 1990s the Chesapeake Bay area began to see a decline in their blue crab population. This huge decline was likely due to the overharvesting of adult crabs, which means there were less juvenile crabs. In 2008, regulations were implemented to try to increase the blue crab population. As of today, the crab population has increased in the area but it is still not where the scientist want them to be.

Videos

Web Resources for Audience to Explore

1. https://cmast.ncsu.edu/cmast-sites/bluecrabs/quiz.html - Test your knwoledge with a short quiz
2. https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Blue-Crab- Learn a little more about the blue crab and their role in the economy
3. https://www.houmatoday.com/sports/20190911/state-issues-reminder-about-changes-to-current-blue-crab-harvest-regulations - Read about the crab regulations put in place for crab harvesting in Lousiana
4. https://www.cbf.org/about-the-bay/more-than-just-the-bay/chesapeake-wildlife/blue-crabs/?gclid=CjwKCAjw26H3BRB2EiwAy32zhShyjbgw0i3qczWpDPv-9JilVhhsCzQTmY-92F3yRrLdSOMFtU_3IBoC0e4QAvD_BwE - Read about the Chesapeake bay foundation and their crab population
5. www.costasinn.com/blog/crabs-baltimore/fun-facts-about-blue-crabs/- Read some fun facts about the blue crab
6. https://myfwc.com/research/saltwater/crustaceans/blue-crabs/life-cycle/ - Read about the life cycle of the blue crab

Resources

“Blue Crab Taxonomy.” BLUECRAB.INFO - Blue Crab Taxonomy, www.bluecrab.info/taxonomy.html.

“Blue Crab.” National Geographic, 21 Sept. 2018, www.nationalgeographic.com/animals/invertebrates/b/blue-crab/.

Bodden, Samantha. “Callinectes Sapidus (Blue Crab).” Animal Diversity Web, animaldiversity.org/accounts/Callinectes_sapidus/#development.

“Evolution.” The Blue Crab Resource, thebluecrabresources.weebly.com/evolution.html.

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