California Bay pea crab facts for kids
Quick facts for kids Parapinnixa affinis |
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| Conservation status | |
| Scientific classification | |
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Pinnotheridae
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| Genus: |
Parapinnixa
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| Species: |
P. affinis
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| Binomial name | |
| Parapinnixa affinis Holmes, 1900
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The Parapinnixa affinis, also known as the California Bay pea crab, is a tiny crab that lives only in Southern California. It's a special kind of crab because it lives inside the tubes of certain worms, sharing their home without hurting them. This little crab was one of the first ocean creatures to be listed as an endangered species back in 1996.
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About the California Bay Pea Crab
The California Bay pea crab is quite similar to other pea crabs in its family, especially P. nitida. However, you can tell them apart by the shape of their main body shell, called the carapace. In P. affinis, this shell is less than twice as wide as it is long.
- Size: This crab is very small! Its carapace is usually about 4.5 mm wide and 2.5 mm long. The biggest ones found are only about 6.0 mm wide and 3.6 mm long.
- Color: Most of these crabs are a light amber color with darker brown spots. But, about 5% of them are albino, meaning they are completely white.
Where It Lives
The California Bay pea crab is found only in Southern California. It has been seen in places like San Pedro, Anaheim Landing, Newport Bay, and San Diego. There was once a report of it being found in Siberia, but scientists think that record is probably a mistake.
Protecting the Pea Crab
The Parapinnixa affinis is very important because it was one of only two ocean crustaceans to be put on the IUCN's list of endangered species in 1996. The other was the coconut crab. Being on this list means the species is at high risk of disappearing forever, and efforts are needed to protect it.
- Living Together: This crab lives in a special way called commensalism. This means it shares a home with other animals without harming them. The California Bay pea crab lives inside the tubes of polychaete worms like Terebella californica and Loimia. The worm provides a safe place for the crab to live.
- Tiny Hitchhikers: Sometimes, a tiny sea animal called a bryozoan (from the family Vesiculariidae) can be found attached to the legs of P. affinis.
How It Was Discovered
The California Bay pea crab was first officially described by a scientist named Samuel Jackson Holmes in 1900. He wrote about it in his book, Synopsis of California stalk-eyed Crustacea.
- First Specimen: The very first crab used to describe the species was a single female. It was found in July 1895 near Dead Man's Island in San Pedro, California. This area is now part of the Port of Los Angeles.
- Lost Home: Sadly, P. affinis no longer lives at Dead Man's Island. The area has become too polluted with "harbor refuse and oil," making it unsuitable for the crabs.
- Later Discoveries: After the first crab was found, no more were collected for over 30 years! Then, one was found in 1930, and more were collected in 1932 by Steve Glassell.
