Why do female blue crabs migrate?
By Chelsie Vandaveer
October 2, 2002
Series: | 1 | | 2 | | 3 |
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading—>Click here.
The blue land crab (Cardisoma guanhumi Latreille) is found throughout the world's tropics. These crabs live in colonies in mud flats, brackish marshes, and mangrove swamps. In Florida, they also select yards where they are considered a nuisance by those who expect lawns to behave like carpets. The problem comes from the aesthetic expectations of the crab colonies. They prefer a nice clean look free of messy vegetation
like lawn grasses.
The crab colonies are never too far from the ocean (crab walking-distance of five kilometers or three miles) and only where the water table is within two meters (6 feet) of the soil surface. Each land crab digs a burrow down to the water table and excavates a 'pool room' large enough to hold one to two liters of water. The burrows are vital for the health of the wetlands; they aerate and mix water-logged soils and provide habitats for other animals.
Near the beach, the water in the burrow is saline or brackish, further inland the water is fresh, but often contains iron and hydrogen sulfide, toxic to most aquatic animals. Blue land crabs adapt to the type of water, they osmoregulate or control the passage of solutes across the cell membranes.
Blue land crabs are scavengers and will eat fruit, insects, and other crabs, but much of their diet are leaves dropped from red and white mangroves (Rhizophora mangle and Laguncularia racemosa). When the rainy season starts in June, the land crabs forage heavily preparing for mating season from July through November.
After mating, the females lay their eggs and carry the egg masses around. When the moon approaches full, the females migrate to the ocean to release the egg masses. The larval crabs spend the first months of their lives as part of oceanic plankton.
The Smithsonian Marine Station at Fort Pierce has an excellent article including a great photograph of a blue land crab (Cardisoma guanhumi Latreille). To learn more about this fascinating creature, click on the link:
http://www.sms.si.edu/IRLSpec/Cardis_guanhu.htm
Series: | 1 | | 2 | | 3 |
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading:
Black Mangrove (Avicennia germinans) Plant of the Week - March 14, 2005
What plant builds islands? Renfield's Garden - October 10, 2002
A tale of fireflies, monkeys, mangroves, bananas, and bats Renfield's Garden - November 28, 2001
What mosquito feeds on nectar? Renfield's Garden - October 16, 2002
Why is the mangrove killifish unique? Renfield's Garden - October 9, 2002
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