Horseshoe Crabs

Are Lucky Here

BY TERRY XUGHE8 STONE HARBOR - Are the winters too cold for you'* How about summer - too much humidity, too hot*’ Do you find the ocean water a little too cold, too dirty? Considered moving to Florida or Califor ma'’ Well,.the horseshoe crabs likes it here just fine, thank you Mark Bottom Ph b candidate in zoology from Rutgers Universtty. who presented a slide show on the horseshoe crab at the Wetlands Institute believes the beaches along I hr* Delaware Bay are the perfect

habitat for the horseshoes "Horseshoe crabs can be found as far north as Maine and as far south as the Gulf of Mexico but the greatest density is on the Delaware Bay This area provides the ideal breeding ground- the beaches are gently sloping and are sheltered from waves, the sand is not too dharse, there are no rocks or coral reefs, and the temperature is moderate." said Botton. Horseshoe crabs, also called helmut or king crabs, belong to the family of orthropods that includes lobsters and other

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crabs. However, the horseshoe is more closely related to the spider or tick. Because they have not changed much over the last 200 million years they are known as "living fossils.” I THIS TIME of the year is the spawning season for the horseshoe crab. The Delaware Bay shore is packed with the crabs as they mate and lay their eggs. "There may be as many as 30,000 per kilometer of the horseshoe variety along the beaches at this time," commented Botton. . It would seem to be a ladies choice-too. For every one female there are five males on the beaches. "Although there seems to be roughly the same amount of male and female crabs in the «vironment for some reason more malcl go out on Saturday night to have a good Hme," joked Botton. The male mates with the female by using a oiasper appendage. The appendage is shaped something like a fist and thumb which locks into the female. Once the male has mated with the female, she deposits up to 3(XXMOOO eggs in 4he sand which the male then fertilizes. The eggs hatch along the beaches and estuaries and develop until they reache the larvae stage. At this point, when the crabs are about the size of a quarter or halfdollar, they are capable of ^rudimentary swimming stroke. This enables them to move offshore and grow, THE CRAB matures by molting- shedding its shell. Once the shell is discarded, the animal takes in water and swells up, thus increasing its size. There are seven molting stages in the crabs first year of life and between two and three meltings for the next couple of years. It takes seven to nine years for the crab to reach adulthood and they can live up to twenty years after that point. , "No one knows for sure how the crabs migrate back to the Delaware Bay shores from the open ocean," said Botton. "One hypothesis is that the horseshoes uses its eyesight. They have good vision; not the type where images can be formed-like man has, £ut they do have the capabilities to detect light. Perhaps they can sense chemical cues like salmon do. We just don’t knoW for sure.” Although the horseshoe can survive tempeiVlures below freezing or above 105 degreesflfchey prefer moderate weather

not strong enough to be active,” said Bot-

ton.

Children often are afraid of the crab’s Ominous looking tail or the supposed vicelike grip of the crab's claws. According to Botton the claws are no more threatening than a baby’s teeth and the tail is- not harmful. "The function of the tail is to right the animal. When the surf flips them over on their backs they push their tail in the^sand and use it as a point of leverage to turn themselves over," he said. THE CRAB eats by trampling and smashing its food with its claws. The mouth is positioned at the base of the legs. Clams, — the soft shelled steamed variety, — are their favorite food. They also eat hard shollod clams by chipping away at the clams shell and pulling out the meat with its claws. "There is a distressingly small afnount of meat on the horseshoes, so they are not eaten, but the Japanese enjoy their eggs," said Botton. The eggr are usually bluish-green in color but can also range in shades of pink or yellow. The natural predator of the crabs are the laughing gulls, sandpipers, large s#a turtles and sharks. In the early 1900’s; a fishery on the shores of the Delaware Bay used to farm the crabs for chicken or pig feed and fertilizer. Although still used as eel bait, the Horseshoe crab's most important used to man is IN biomedicai research. Scientists used the blood from the crab in LAL tests to determine whether or not gram negative bacteria is present in a culture. The crabs blood coagulates when endotoxin, the dangerous substance in gram negative bacteria that spreads disease, is present. Pharmaceutical companies also use the crab’s blood to test drugs for purity. Unlike human’s red blood which possess hemoglobin, the crab’s blood contains hemocyanin which gives it an aristocratic blue blood. In addition to this being the spawning season of the horseshoe, Cape May County residents have the opportunity to see another spectacular natural phenomena. Anne Galli, assistant director of the Wetlands Institute, said that shorebirds will be returning northward during May and ,June. These birds stop and refuel in Cape May County before heading north to thte artic tundra.

"Sometimes in the winter or early spring you may find crabs washed up on the

beach in, groups. Because they are cold* Terry Xughes of Avalon is a freelance

blooded, they lie dormant. They are just^—wr/ter.