Every year, we have a couple of Atlantic deep-sea red crabs (Chaceon quinquedens) in our tank at the Oceanarium at Hampton Beach.
This year, we were able to get them from Jillian Robillard at Southern Maine Crabs in Kittery, Maine. Jillian graciously kept several deep-sea spiny crabs and three deep-sea red crabs for our tanks at the Oceanarium.
Deep-sea Atlantic red crabs are one of the latest culinary delights found in the seafood market.They are a sweet, tasty crab making the rounds of the restaurants. Little is known about the red crab as they are usually found from 700 feet to over a mile down the canyons, off the Southeast side of Georges Bank and mid-Atlantic bight.
Surprisingly, a small resident population occurs 15 miles southeast of Hampton, N.H., in Scantum Basin in the Gulf of Maine.Local fishermen occasionally catch them, but there is not a local fishery for them. Scantum Basin goes down to about 450 feet, not nearly as deep as the canyons, but there is a small pocket of very cold water entrapped there. These crabs seem to have a very small range of temperature and salinity they can tolerate. One or two degrees too warm, and they will not survive.
What we know about them is what we can observe when they are in captivity or from the NOAA robotic subs that reach far into the depths to provide us with snapshots of life in the abyss.
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Interestingly, red crabs are in the same family as the swimming crabs, such as blue crabs and lady crabs, but they lack the specialized last leg these other crabs use to paddle on the surface of the water. Their claws are extremely sharp, elongated and strong, like a blue crab. My interns are reluctant to pick these crabs up for fear of losing a finger! I haven’t been able to find any studies done on their unique eyes.They are a distinctive color, deep red like night vision goggles! When the crab is brought to the surface and out of the water, the light is obviously too bright, and they pull their eyestalks back into the sockets and freeze in position. Their eyes are one of the many adaptations they must have developed to survive in the abyss.
These animals climb up and down the canyon walls. The Gulf of Maine is not 5,000 feet deep. At its deepest, it reaches maybe 1,200 feet. Red crabs appear to climb up the sides of the canyons during different periods of their life. The females climb into shallower water when their eggs are about to hatch. The larval red crabs then hatch and are released into the water column and slowly sink to the depths as they mature.
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All crustaceans have a semi-closed circulatory system. That is, they have blood vessels but also pump seawater throughout their body beneath their exoskeleton, allowing them to regulate their internal pressure. Thus, allowing them to navigate up and down the sides of the canyons without developing the “bends.”
Last year, we had a male and a female red crab in our deep-water tank. Unbeknownst to us, the female was about to molt. One morning, I came in, and the male crab had wrapped himself around the female. For days, they stayed in this position, with the male protecting the female and feeding it scraps of food. This went on for a couple of weeks, and then one morning, I came in and the female had molted. For the next couple of days, the male and female remained attached to each other but in all different positions.
Finally, they were head-to-head face to face, and the female lifted her tail to allow the male to impregnate her.This lasted, believe it or not, for a full 19 days, at which time they went their separate ways. I have no idea how long the female will carry the fertilized eggs internally, but if the lobster is any example, it may be up to a year. They release the eggs onto the underside of their tail and hold them until they hatch into a free-floating larval stage. This could take up to another year. According to researcher Brad Stevens from the University of Maryland Eastern Shore, they probably reproduce every two years like the lobsters. No wonder crustaceans are so crabby. Imagine being pregnant for a couple of years!
Red crabs have only been commercially fished for about 30 years, so little is known about their biology and reproduction. The National Marine Fisheries Service has deemed them a data-poor stock.
Only the male crabs are fished, and the claws and legs are sold as picked meat.
I’ve never eaten a red crab, but I imagine they are just as delicious as all the other crustaceans, especially when dipped in melted butter!
Ellen Goethel is a marine biologist and the owner of Explore the Ocean World at 367 Ocean Blvd. at Hampton Beach.
