aybe it is their duality: periodicity, recording them in equivalent a benign nature coupled numbers at high tides both day and night with a bizarre, almost throughout much of the prime spawning otherworldly appear- months of May and June. During what ance: a crusty Darth might be termed their mating arribadas, Vader helmet enclosing the females, some as much as a foot wide, an articulating chaos of are typically observed dragging along Slow M jointed, pincer-tipped legs one or more clinging males. that look dangerous, but Somewhat reminiscent of a nesting are not; hauling a spiny sword of a tail turtle, a female (hsc) that looks like a dreadful weapon, but is intent on reproduction excavates a actually harmless. hand-deep depression in wet sand for What is it about the members of Slow Nation that so fascinates us? Nation Or maybe it is their mystery: When the her nest. The larger she is, the more planet seems filled with the fluid of light eggs she will deposit. A male fertilizes and salt, these markers of high tides and her eggs as she deposits them. Since it spring’s flowering seem to arrive magi- is an external fertilization, more than cally, sloshing sensually around in the one male may father her young. Biologist warming waters of our embayments as Alison Leschen [formerly with the Mas- if drunk on the newly-long days, bent on sachusetts Division of Marine Fisheries love when the full moon hangs, cham- (DMF) and now the Reserve Manager at pagne-colored, in the night sky. Waquoit Bay National Estuarine Research Or perhaps, if we have seen them on Reserve] and her colleagues have con- their backs on wave-washed beaches, ducted research on in Pleasant awkwardly struggling to right them- Bay, Cape Cod. She reports that females selves, we identify with an endearing “return to the breeding beach in waves,” klutzy aspect to their character and em- to deposit 1-15 golf-ball-sized clutches pathize with their travails. That they can of eggs per nest in a series of a dozen or right themselves at all is an evolutionary more individual nests. and gymnastic feat. During this reproductive marathon, The scientific name of these strange females may produce up to three mul- organisms, Limulus polyphemus, roughly tiple-clutch nests per tidal cycle over translates as “askew one-eyed giant” a period of two or three cycles. The or “sideways-looking Cyclops” and was final total amounts to a lot of eggs: “For probably derived from a mistaken belief example,” says Leschen, “a large female that the each had but a single could lay 8 clutches of 1200 eggs in each eye. (Polyphemus, son of Poseidon in of three different nests, return a second Greek mythology, was a giant Cyclops time on another tide and do the same, who enjoyed snacking on humans; he ate and lay a total of [from] 58,000 to 63,500 six of Odysseus’s men. His name is also eggs.” Other researchers have estimated given to one of our large moths with an annual egg production as high as 88,000 eyespot on each hindwing.) The members eggs per large female. of Slow Nation are, of course, horseshoe The eggs are soft and gelatinous when crabs, captivating creatures of manifold first deposited, but quickly harden to strangeness; aliens from a long lost, an- resemble BB-sized pepper corns. About cient Earth that still live among us. five days later, a proper tailless baby Resembling giants’ fingernails digging crab becomes discernable inside the egg. in the sand, horseshoe crabs congregate The tiny crabs hatch in 2-4 weeks and to mate at the high tides of late spring and emerge from the sand when liberated early summer in the ancestral swash wa- by a high tide. Equipped with spines ters and intertidal muck near the crest of to deter predators, they drift and slosh the water’s reach. While some authorities about as plankton in tidal waters for three have reported that peak breeding occurs weeks, then settle down on the intertidal by Lee Stephanie Roscoe during the new and full moon dates, es- substrate. pecially at night, others report no such Photo © Bill Byrne 24 25 No one knows for sure, but it is esti- sedimentary rocks in Manitoba, recogniz- Cryptic Median Eyes mated that only 10 or fewer of the eggs able horseshoe crabs have been around produced annually by a large female will for nearly half a billion years. They have safely hatch and survive their planktonic swum through epochs, navigated around and juvenile stages to reach adulthood. dividing continents, been pushed about Female horseshoes are ready to breed at by the rise and fall of mountain ranges, around nine or ten years of age, while the and have spawned on the shores of un- males (preferring older women) are ready named seas that came and went long, long at eight years or so. Both sexes can live ago. They have survived asteroid strikes until about 20. It is not the crabs them- and numerous worldwide extinctions, selves, but the elements of the “mobile seemingly pulling their ocean world ever ecosystem” that they carry around on onward to the present. The oldest known Prosoma their backs – including barnacles, lim- prototype is named Lunataspis aurora:

Lateral Compound Eye The first pair of walking legs provides pets, sponges, slipper shells, and algae “crescent moon shield of the dawn.” Two an easy way to identify the sex of a -- that help scientists determine their age. fossils, both of 1.5-inch specimens, have After mating, the adult crabs return from been discovered so far, but it is not yet horseshoe crab. That of the male, left, the intertidal gathering areas to the sub- known if these are tiny, full gown adults, is modified to grasp a female during tidal zones where they will spend most or simply juveniles that would have grown spawning, while that of a female, of their lives on the bottom, bulldozing to larger size. right, ends in a conventional pincer through the benthic landscape in search The hsc body is divided into three ma- claw. Collapsible, spatulate tips on of food items such as marine worms, last pair of walking legs, below, aid jor sections: the prosoma, or carapace, Opisthosoma algae, and shellfish. which houses six pairs of walking/feed- the animals in moving over soft sand ing appendages and most of the internal and mud bottoms. Evolution & Anatomy organs; the opisthosoma, which is hinged There are only four species of horseshoe to the prosoma and houses the book Movable Spines gills; and the telson, or tail spine, which crabs worldwide, all of which diverged Telson from a common ancestor, Mesolimulus is situated in a hinged pocket at the base walchi, about 150 million years ago. Our of the opisthosoma and equipped with species, the American Horseshoe Crab, light-sensing organs. The chelicerae, out- Dorsal View is the only one that inhabits the Atlantic. fitted with pincers and used primarily to It ranges from Maine (where it is scarce) locate and grasp food, are the first and First Walking Leg (male) down to Florida, and from there all the way smallest pair of appendages near the around the Gulf of Mexico, to finally fade front of the shell (and are a feature shared with spiders and scorpions). They are

out on the northern tip of the Yucatan. Chelicera followed by five pairs of walking legs. On Horseshoe crabs are in the family the male, the first pair of these terminate Photos © Bill Byrne Limulidae and the phylum Arthropoda, in mitt-like appendages with a single claw, for rhythmic propulsion while swimming but are placed in their own class, Meri- somewhat comparable in look to an old (especially by the juveniles). The first stomata. They are not crustaceans and fashioned can-opener. They are used to pair of gills is called the operculum. It have no relation to the true crabs (which, clasp the female while mating. serves as a protective cover for the other among other things, lack compound eyes five pairs, and also houses the opening of and bear their eyes on stalks). They are On the female, this first pair of legs is the same as the next three pairs on both the genital pores through which eggs or thought to be related to the long-extinct sperm are released from the body. trilobites, or perhaps the equally long- sexes, ending in pincers similar to those on the ancillary legs of a lobster, and The telson – which people often fear extinct sea scorpions (and may even be is a stinger – is a harmless rudder and progenitors, rather than descendants, of exhibiting the same lack of force when it comes to gripping humans. (Place a junior “righting organ.” A hinge in the body, that group), but among surviving organ- along with the telson, allows the isms they are most closely related to the crab on your hand and there is an almost trusting delicacy to the feel of its legs on to torque itself into different positions in

spiders and scorpions. The class name Mouth your skin.) The fifth pair of legs, larger water and on land, rather like a dancer

means something like “thigh-mouth” in Operculum and longer than the rest, are equipped doing a contraction exercise. When an Greek, which is an appropriate sobriquet Book hsc finds itself upside-down (a com- since the horseshoe’s mouth is located at with collapsible, multiple-leaved “spatula feet” that, like a pair of snowshoes, help Spatulate Leg Gill mon and life-threatening predicament the center of the legs where the “thighs” all during the breeding season when many originate. Food is ground up with spines the animal to navigate efficiently across soft sand and mud bottoms. are upended by surf) the telson, used at the bases of the legs as the animal Telson Behind all the legs are six pairs of book Anus in coordination with body contractions moves along. and movable spines on the opisthosoma, Based on recent fossil discoveries gills containing sheaves of page-like re- spiratory organs that can also be used Ventral View will often allow it to flip itself back over. from 445-million-year-old Illustrations © Debra Silva Using its legs, jointed body, flapping gills, 26 27 and telson, an hsc can swim rightside-up Young crabs molt very often and usually or upside-down, and can burrow into in summer, while older crabs, if they do sand to escape predators or survive a so at all, tend to molt in autumn. The stranding. So long as its gills remain chitinous, spiky shells of the juveniles moist, a crab can live out of water for are pliable and more like your fingernail days at a time. than the much thicker, harder, smoother Limulus has nine, mostly cryptic eyes. shells of adult crabs. The older the crabs The larger, lateral, compound eyes, each get, the more slowly they grow, and the containing about a thousand individual intervals between molts lengthen until lenses, are the only obvious ones, and they finally stop altogether. Dave Smith, are probably the most important for Limulus biologist par excellence at the identifying potential mates. These have USGS, says: “Females are larger than the largest rods and cones of any known males because they mature one or two animal, roughly 100 times the size of our years after males of the same cohort. The own, making the hsc an important subject extra molt or two [allowed by the delayed for researchers studying various aspects maturity] allows them to grow larger.” of vision. Less easy to see without a microscope is another rudimentary eye Gifts & Threats behind each lateral one. Then there are Human interactions with horseshoe two median eyes in the top of the shell, crabs have been extremely beneficial to front and center, surrounding one endo- us, but generally detrimental to the crabs. parietal (“within a cavity”) Cyclopean Indigenous and colonial populations col- eye. On the underside, just in front of lected them by the thousands to fertilize the chelicerae, is yet another pair of eyes their fields, and by the 1800s, millions of which may help the crab remain balanced the crabs were being collected and ground while swimming, and are also thought to up to feed hogs and poultry. As family help perceive food items. In addition to farms gave way to suburbia and the coast all these eyes, the telson is equipped with was increasingly developed for vacation photoreceptors which may help a partially homes in the 20th century, exploitation buried animal discern day from night. of the crabs for agricultural purposes Like all members of their family, horse- declined, while disruption, degradation, shoe crabs must periodically shed their and outright destruction of their nesting entire exoskeletons in order to grow. habitat gradually increased. Photo © Bill Byrne “Thigh mouth” is an appropriate name for the horseshoe crab, since the mouth is located at the center of the legs and food is ground up by their action. The chelic- erae (paired claws above the mouth) are used primarily to find food and pass it to the mouth. Right, horseshoe crabs must periodically shed their shells in order to

grow. This discarded shell shows the opening the crab used to exit the old shell. Photo © Bill Byrne 28 29 At the same time, a growing number of able medical use. They soon developed unharvested population,” he says, “sex It is almost certain that habitat destruc- scientists began to turn their attention a process to extract and purify LAL, ratio on the beach is expected to be tion has also played a part in the decline, to the hsc as a research subject. Start- which was then used to test medicines, more like two-to-one or three-to-one on and some biologists think this may be the ing in the 1920s, Dr. H. Keffer Hartline, a vaccines, medical devices, and blood average – although you might see a ratio greatest impediment to recovery. Naviga- researcher at the Marine Biological Lab infusions for bacterial contamination. It much higher than that on any given high tional dredging through sea-bottom sedi- in Woods Hole, began using horseshoe was so fast and effective for this life-sav- tide. So, nine-to-one is high, and indica- ments to keep channels open disrupts crabs to study vision. That work would ing purpose that the U.S. Food and Drug tive of female-biased harvest.” the benthic habitat, while in-shore, the eventually lead to a 1967 Nobel Prize for Administration accepted it as a standard Because horseshoe crabs include building of sea walls, piers, wharves, and Hartline and two other scientists who test for endotoxins in 1983, creating an shellfish in their diet, shellfishermen long jetties; “beach nourishment” projects (a discerned how images are received, ever-growing, worldwide demand for regarded them as competitive enemies. 2009 thesis reported 45 beach fill projects transmitted, processed, and perceived the product. on Cape Cod alone in a 5 year period); through the crab’s optic system. Much All efforts to artificially replicate LAL of what we know about our own eyes and in the laboratory have failed, so horse- Otherworldly Applications the physiology of vision came directly shoe crabs remain the only source of from the study of hsc eyes. That research this precious substance. The result has The horseshoe crab’s ancient proteins and enzymes continue to provide useful agents of use work continues, and it was recently been the development of commercial to people, offering a compelling example of why allowing the extinction of any species has the proven that sight helps the male crabs “extraction and return” procedures that potential to deprive future generations of as-yet-unimagined, lifesaving discoveries. The chitin find mates (as do pheromones). Other involve the collection of live crabs by of which the hsc shell is composed is being developed for use in sutures and burn dressings. subjects of ongoing hsc research include hand or dredge, careful transport of the Elements in hsc blood (in addition to LAL) are being investigated to detect viruses, parasites, its biological clock, visual detection of animals to a laboratory, and, following and fungi, as well as bacteria. NASA is experimenting with a portable, hand-held device not movement, ultraviolet light perception, the extraction of approximately 30% of much larger than a cell phone that uses elements of hsc blood to test swabs from spacecraft for and how vision sensitivity increases or their blood volume with a heart-pierc- contamination from earth, and potentially to detect alien microbes contaminating spacecraft decreases de pending on the intensity of ing needle, transport back to the sea for that return to earth. Ironically, one of Earth’s oldest and most primitive species may, as NASA’s light/time of day. live release in the area where they were planetary protection officer hopes, “protect life on other planets in our solar system,” from While the crabs have given us great gifts collected. Research indicates that blood the contaminating activities of one of its youngest and most intelligent species. in terms of understanding the chemistry volume returns to normal in a week or and physiology of vision, an invaluable so, although the blood cell count may A 2006 DMF news release reported: and even beach cleaning/manicuring property of their blood, discovered in take two or three months to return to “Several Massachusetts towns offered operations interfere with breeding/egg 1956, has literally saved millions of hu- pre-extraction levels. a bounty of three cents on the tail of a development and kill animals outright. man lives. Horseshoe crabs, as befits Studies conducted by LAL manufactur- horseshoe crab. In the early 1960s, the As DMF’s Vin Malkoski says, “It is pretty creatures of such ancient lineage, are ers indicate the entire process results in Town of Chatham paid $1,500 in total disconcerting to be doing a spawning genuine bluebloods: unlike the hemo- the fatality of about 3% of the exploited bounty on crab tails, which at three cents survey and have a town tractor come globin of our own blood, which employs animals, but other researchers have each equals 50,000 horseshoe crabs. A by, driving over and sweeping up the iron to transport oxygen and is therefore reported mortality rates of 10-15%, and review of towns’ annual reports suggests wrack line where the crabs are laying red in color, the hemolymph of hsc blood some as high as 30%, depending on how that half-a-million crabs or more were their eggs.” uses copper to transport oxygen, and as much blood is drawn, body size, and killed annually as part of local shellfish Other man-made deterrents to con- a result, appears blue. It was discovered how long the animal is handled. While predator control programs.” as early as the 1880s that horseshoe crab tinued Limulus population abundance reporting regulations vary from state to During the 1990s, crabs became ex- include the usual pollutants – hydro- blood had unusual clotting properties, state. Associates of Cape Cod (the Woods but it was not until the 1950s that Dr. tremely popular as a bait to tempt whelks carbons, fertilizers, pesticides, heavy Hole-based sole manufacturer of LAL in (conch) and American eels (themselves metals, and the like – that wash down the Frederick Bang, working at the Marine Massachusetts) must report the names of Biological Laboratory at Woods Hole, no longer plenteous) into traps. Millions streets of America and eventually into the fishermen they buy from, the number were harvested for this purpose up and the ocean. Because they won’t mate in discovered that it clotted in the presence of horseshoe crabs they purchase, and of certain bacteria. down the East Coast, reaching a peak of the murky, high seas of stormy weather, “the number of crabs received dead or 6 million (more than 2,500 tons) taken it seems likely that anthropogenic climate This discovery led to more directed rejected and the number of dead crabs in 1997. This commercial bait harvest change – with its weather extremes, ris- research, and Bang and his associates returned to the biomedical fishermen” was almost certainly the primary cause ing waters, and effect on ocean salinity soon determined that it was bacterial to the DMF each year. of their precipitous decline in Delaware – could also add to their travails. endotoxin (found in the cellular mem- In areas where crabs are harvested for Bay (and probably elsewhere) during the branes of the bacteria that cause spinal Of course, sidelong-glance Cyclops also biomedical purposes, females -- preferred past two decades, although beach fill has its own wild predators and natural meningitis, toxic-shock syndrome, gon- for extraction because of their larger size projects and shoreline alterations that orrhea, and typhoid, among others) that obstacles to survival. and fishes and therefore greater blood volume damage or destroy spawning habitat are gobble them up as eggs and young. Sharks triggered the reaction, and that the clot- – appear to be fewer during the spawn. also undoubtedly implicated. Regard- ting factor itself was a chemical released and sea turtles chop up and consume Biologists reported that in Pleasant Bay, less, the decline became so obvious that adults. Seagulls keep a continual watch by certain hsc blood cells (amebocytes). after years of intense harvesting of crabs conservationists, LAL manufactur- The researchers named this reagent and attack any upended crabs they can for LAL, the ratio of spawning crabs was ers, and ordinary beachgoers began reach. (The crabs are not incapable of at Limulus amebocyte lysate, or LAL, and nine males to one female. This is pretty to raise alarm and demand better hsc quickly recognized its potential for profit- least one form of revenge, however: many unusual according to Dave Smith. “In an conservation. contain encysted, parasitic flatworms 30 31 areas on the Cape are under review as of this writing. Malkoski says, “We had critical habitat for the species.) While some problems in 2011 as some groups hsc egg production in Massachusetts lost support/funding and others seem to may not be enough to make it a keystone be experiencing volunteer fatigue. [We] species here as it is around Delaware Bay don’t know how 2012 is going to go.” and the Cape May peninsula, it likely was historically when the “wahquoits” (as Other Research the indigenous locals called Red Knots) Getting a solid handle on hsc population inhabited Barnstable county in the many numbers and trends is obviously difficult, thousands in the 19th century, coinciding but more formal studies to determine with copious crabs and unaltered beach such things as hsc habitat use and mi- habitats. gration patterns are yielding interesting As concern for the hsc and its resource- discoveries. For instance, it now appears deprived predators was raised by con- that horseshoe crab populations are lo- servationists and the LAL industry itself, cally discrete, and that their members the agencies responsible for the con- mate, breed, and overwinter in relatively servation and regulation of our natural small areas. If this theory holds up, their resources responded. The Atlantic States attachment to a singular place makes Marine Fisheries Commission (ASMFC) local hsc populations especially vulner- determined Limulus was in trouble in the able, since new, incoming crabs will not 1990s, and put together a paper outlining readily replace extirpated populations. its concerns and a proposed management It also means that local populations may plan in 1998. Our own DMF initiated state regula- Horseshoe Crab Photo © Bill Byrne tions to conserve Limulus in 1999, and Spawning Beaches Biologists have identitifed at least 11 species of shorebirds that rely in part on its personnel sat down together with horseshoe crab eggs to fuel their northward migrations to breeding grounds in assorted scientists from other states 2004 the spring, an important reason to maintain the crabs in abundance. S and institutions such as URI, Cornell N N

that will hatch and mature in a gull’s which otherwise could not probe to the University, the United States Geologi- SSS digestive tract!) level where hsc eggs are deposited. cal Survey (USGS), and many more to N+ Coinciding with the rapid decline in develop a new protocol for surveying hsc numbers in Delaware Bay due to spawning crabs by coordinated volun- Alarm & Conservation teers working under professional biolo- Starting in the late 1980s, as beach overfishing and other human activities, researchers reported that several spe- gists. The resulting data would be used to goers noticed the once-abundant living supplement other prior and subsequent cies of shorebirds also began to decline S SS cobblestones no more bumbling up to research, formal and informal alike, as S in numbers. No species exhibited a more N SS their nude feet on the beach, concern well as trawl data. S for the species began to swell. Conser- alarming decline than the Red Knot, vationists realized that, at least in some Calidris canutus rufa, a shorebird that Horseshoe crab nursery sites in the Commonwealth occur from the north parts of its range, the hsc is a keystone feeds almost exclusively on horseshoe S S shore to the south shore, from Mas- N N S species, the lintel at the top of an eco- crab eggs to refuel during its marathon SN S NN migration of over 9,000 miles from Tierra sachusetts Bay to Cape Cod Bay, from S logical structure, which, when destroyed, N causes a cascade of devastation that del Fuego to the Arctic. As hsc numbers Buzzards Bay to Nantucket Sound and N the Vineyard. Currently monitored areas N encompasses many other species. In the evaporated in the 1990s, the Red Knot N S N population declined by some 70 percent, include sites in Pleasant Bay (Chatam), NN NN case of the hsc, it had long been known N NS S NN NNN Wellfleet Bay, Waquoit Bay, and Monomoy NNNN N SS N falling from 100,000 birds to about 15,000. N S S S that at least 11 species of migratory birds S S N N When the crabs had been abundant, hsc NWR, as well as some in Barnstable Bay, NS NN SN relied on crab eggs as a crucial energy NNS S S N Buzzards Bay, Pleasant Bay (Duxbury), SS N source during their spring journeys to eggs were recorded at 40,000-100,000 S S S N Westport Harbor, Nantucket, and Mar- S SSSN northern breeding grounds; that hsc per square meter of beach. Following S the crash, those figures dropped to tha’s Vineyard. S S eggs in the sand provide an important S NS N food source for millions of resident and about 1,500 eggs per square meter and In 2010, 21 beaches in Massachusetts S N N S Red Knots went from gaining 9 grams of were surveyed “by over 250 volunteers N NN N transitory shorebirds throughout the S S SNN SS crab breeding and incubation period. weight per day to only 2 grams. The link and staff from government agencies, N The more crabs there are churning up was unmistakable. environmental organizations, and local the sand, simultaneously digging up As of January, 2012, the Red Knot is service groups.” Data from these surveys a Major Spawning Beaches previously deposited eggs as they work under consideration for listing by the (as well as those from harvesters and to bury fresh ones, the more eggs are USFWS under the 1973 U.S. Endangered other studies) go through DMF’s Vin e Minor Spawning Beaches exposed to the varied lengths of beaks Species Act. (Monomoy NWR and other Malkoski and have not been collated as 32 33 be genetically distinct and limited to only distinctive signal, which is in turn picked one or a few specific spawning sites. Both up by 22 “Thermos-sized” receivers factors may make them more vulnerable “moored in cement tubs,” then down- to extirpation. loaded to the researchers’ laptops. Dr. Mary-Jane James-Pirri of the Univer- The acoustical transmissions have not sity of Rhode Island, assisted by the U.S. yet been fully tabulated, but based on pre- Fish & Wildlife Service, tracked the crabs liminary findings, Malkoski is not afraid in Cape Cod’s Pleasant Bay from 2008 to say that the data indicates that, “Crabs to 2010 using both acoustical and static tagged on spawning beaches in enclosed (non-transmitting) tags, showed that the embayments tended to have strong site crabs migrate to local sub-tidal areas af- fidelity, while those from more open areas ter spawning, and then go to over-winter tended to roam around more.” in waters not much more than 30 meters Other methods of getting data include down. Journeys to the continental shelf trawls. A recent DMF report states: “Ap- may be limited or non-existent. She writes proximately 100 tows are made in five that “Isotopic signatures of horseshoe bio-geographic areas, following a strati- crabs from embayments within Pleasant fied random sampling design, with 22 Bay… Stage Harbor… and Barnstable total strata.” Malkoski notes that hauling Harbor… were found to be significantly some of the tagged crabs in the late fall, he distinct, suggesting that crabs remain and his colleagues have so far found that within localized areas long enough to while a few are dragged up from deeper acquire the isotopic signature of the waters by commercial fishermen, most embayment.” She has also noted that of their retrieved crabs were hunkered “Genetic population subdivision over a relatively small geographic area has been Horseshoe crab researcher Katherine Photo © Katherine Terkanian documented for horseshoe crab popula- Terkanian and colleague Nate Bent Report Tagged Horseshoes! tions in the mid-Atlantic [coast].” survey for breeding crabs on a Cape Researchers use several different kinds of tags to mark and track horseshoe crabs. There are Katherine Terkanian and her cohort, Cod beach. two basic varieties: active tags which transmit acoustic and/or electronic signals (on top of Sarah Martinez, both Master’s female, above), and passive, non-transmitting button tags (on side of female, plus close-up) candidates at the University of or spaghetti tags which come in various shapes and colors and typically include a unique tag Massachusetts who labor out of number and a USFWS phone number to call if the crab is found. As with bird bands, the idea is Massachusetts Audubon’s Wellfleet to document the location of individual animals over months and years, dead or alive, and then Bay office, are continuing the work. to analyze the ever-accumulating data to determine movement/migration patterns, longevity, Terkanian asks: “Are Massachu- and other information that can help direct management efforts. (So far, most crabs appear to setts horseshoe crabs a singular be quite prudent in the distances they travel, but there are exceptions such as one that was population, or are they comprised tagged in Wellfleet in 1998 and ended up in Narragansett Bay in 2007. If you find a tagged of sub-populations around the crab, record the color and number of the tag, and call 1-888-LIMULUS (USFWS) to report it. coast?” She is conducting DNA You may receive a pewter horseshoe crab pin for your efforts. studies on the crabs, mostly those from populations on the Cape, but has yet to tabulate and analyze the down closer to shore (as expected). greater blood volume.” These may be accumulating data. In general, trawl catch data shows a factors determining population numbers continuing decrease in hsc numbers, and recruitment. “I once saw many, many Martinez asks: “Where do the males clustered around a rubber tire left horseshoe crabs go to after spawn- but because the trawl cannot operate in shallow, inshore waters where the crabs on the beach,” she reports. “Perhaps the ing? How far out do they go? How largeness of the round, dark tire, like a deep? Are spawning groups limited may concentrate, significant numbers may be missed. bigger size of Limulus female, might at- to very local areas for breeding, and tract more mates!” over-wintering?” Working on a joint “There is a great deal about crab project with DMF, she is assessing populations which remains unknown,” populations around Wellfleet Har- Terkanian says. “It may be colder waters A Restoration Response bor, Nauset Estuary, Stage Harbor, produce smaller animals, warmer waters, While the horseshoe crab may not be and Monomoy, Chatham. She has larger. For instance, crabs in Cape Cod able to change much, humans in their attached acoustical telemetry tags Bay are smaller than those in the Sound, relationship to it can and have. With to 75 crabs to see if they migrate out and… in Georgia the crabs are compara- an as yet incomplete understanding of to Nantucket, Monomoy, or further tively much larger than here.” Why might crab abundance and recruitment -- and offshore. Each receiver velcroed and size matter? “Larger females carry more some anecdotal accounts disturbingly glued onto an animal’s shell sends a eggs,” she says. “Larger females have suggesting that populations are below Photo © Bill Byrne 34 35 Mature crabs that no longer shed Prescott mentions that around his turf their shells on an annual basis often For more information: at Wellfleet Bay, numbers have plum- accumulate large numbers of hitch- meted since the 1980s, but he is hopeful hikers. This one is hosting a profu- www.ceoe.udel.edu/horseshoecrab that nature may create new opportunities sion of slipper shells. PBS’s “Crash, A Tale of Two Species” a for recovery: “A blizzard created a break film by Alison Argo:www.pbs.org/wnet/ and wash-over in a beach at Pleasant 90% of what they used to be and might nature/episodes/crash-a-tale-of-two- Bay which created a whole new area for disappear completely -- it is vital that species/introduction/592/ horseshoe crabs [to spawn], as well as we must. Shellfishermen now realize the And for a great little book on the for least terns, piping plovers and dia- crab is a friend that eats clam worms, subject: mondback terrapins. That’s how barrier and even more importantly, turns over beach ecology works.” and aerates bottom sediments, allow- Extraordinary Horseshoe Crabs by Julie Dunlap With its slow, bumbling nature, leav- ing more organisms such as clam spat ing its shell like an ancient tribal mask to grow. Rumors of illegal collection on the sands, delighting children with abound, but most shellfish harvesters proactive, and notes that its harvest its “sword,” the horseshoe crab defines want to cooperate. closure, “…was initially opposed by the coastal areas in early summer as it churns “There are so many stakeholders,” State of Massachusetts, which contended itself over, moving into the near surf, in Terkanian says. “Sometimes the har- that the National Park Service usurped areas redolent of sea and algae and wrack, vesters think the biologists are trying state authority to manage the harvest of while gulls, terns, and shorebirds stoop to harm their livelihood. We’re not. We fish and shellfish. It was subsequently and cry overhead. With protection and want to do the science for the sake of determined that the closure was within continued research, and a determination all concerned. There are so many uses NPS [National Park Service] authority be- on our part to conserve them for both of the crabs. We want to protect them cause horseshoe crabs are not classified selfish and altruistic reasons, Slow Nation for their own sake, and the sake of the Photo © Bill Byrne by the state as either fish or shellfish.” A should remain with us for generations to ecological niche they inhabit. We want sometimes offered at public hearings is survey in 2001 showed the highest densi- come. In fact, if geologic history offers to understand them to conserve them as to set even larger width restrictions to ties and largest crabs on Cape Cod were any guidance, horseshoe crabs will likely a resource for humans.” limit the take of females. Surveys of ju- spawning on Monomoy NWR, and ratios remain long after we have gone. The collection of crabs for all uses is venile crabs to determine their mortality of females to males are higher than on down. A DMF report states “In 1999, 151 levels are also under consideration. Mass the mainland. In 2011, “Approximately 598 Lee S. Roscoe is a playwright and freelance fishermen reported harvesting 545,715 Audubon’s Bob Prescott suggests: “We horseshoe crabs were tagged on Morris writer. Her articles appear frequently in the horseshoe crabs for bait and for biomedi- need regional horseshoe crab spawning Island and on North and South Monomoy Barnstable Patriot, and her feature on the cal use.” In 2010: 54,782. (No one knows sanctuaries. We need regulations that Islands,” and reports of these animals in Sandwich Hatchery centennial will appear if this is because of stricter regulations will allow the hsc population to return the years to come may prove useful in in Cape Cod magazine this spring. She or diminished stocks, but the limit set to pre-harvesting levels. It isn’t about assessing survival factors. occasionally gives walks through www. on take is now 165,000 crabs; three sustainability; it needs to be about re- The jury is still out, but it well may be capecodwalks.net and is the author of times higher than what is being landed.) building the stocks.” that the complete closure to harvest on the book Dreaming Monomoy’s Past, There is now strong pressure to keep hsc Most strikingly, in places where har- Monomoy has helped the crabs recoup Walking Its Present. Our readers may conservation a priority, however, and it vest has been limited throughout the beyond those on the mainland. But then remember her previous articles on such is supported by government agencies local range, there is some evidence of again, Monomoy has always had big diverse subjects as didemnids, tiger beetles, such as DMF and the USFWS, as well recovery. By current ASMFC assess- hsc numbers: Prior to regulations and and fireflies. as non-government entities such as the ments, numbers are still down in New closures, the NWR Massachusetts Audubon Society and the York and New England, but increasing in yielded the highest Horseshoe Crab Conservation Associa- the Southeast and Delaware Bay where harvest of horseshoe tion on Cape Cod. DMF has a difficult bal- closures have been strict. However, in crabs anywhere in ancing act between conserving species those areas other factors must also be Massachusetts in and allowing human use of the resource. taken into account. These would include 1999. In the 1950s, the Since 1999 it has received high marks for warmer water temperatures allowing for crabs abounded there its efforts at conservation. more frequent matings from larger, more in the thousands; the DMF continues to issue stringent regu- productive females, and also habitat refuge manager com- lations which protect Limulus during its availability/protection. mented in an official critical spawning period, including com- Two key federal entities involved in report that it was plete closure to harvest all over the state Massachusetts are the Cape Cod National “too bad we can’t find during the new and full moon periods of Seashore and Monomoy National Wildlife an economic use for May and June. When harvest is permitted, Refuge. Since 2000, they prohibit any col- them.” there is a take limit of 400-600 animals, lection within their boundaries (which and a size limit that protects animals less extend a ¼ mile out from their shores). than 7” across the prosoma. A suggestion The National Seashore was particularly Photo © Bill Byrne 36 37 Division of Fisheries & Wildlife NONPROFIT ORG. Field Headquarters Westborough, MA 01581 U.S. Postage Paid Leominster, MA Permit No. 17 No. 1, 2012 $3.00

A pair of mating horseshoe crabs, the male clinging to the larger female, nest on a beach at high tide in late spring. These ancient creatures, unrelated to the true crabs, come ashore at many of our beaches in May and June to lay their eggs. The female digs a hole and deposits golfball-size clumps of eggs, which the male fertilizes exter- nally. She may lay tens of thousands of eggs in a season, but it is estimated that fewer than 10 will survive to adulthood. The eggs are eaten by a great variety of shorebirds, including some that are almost wholly dependent on this seasonal, high calorie food supply to provide them with the energy they need to complete their spring migration and arrive on the breeding grounds with enough reserves to survive the rigors of egg production and chick rearing. Significant reductions in horseshoe crab populations, which support both commercial bait fishermen and medical products extractors, have become a great concern of conservationists. Photo © Bill Byrne

Inside This Issue: Horseshoe Crabs, Woodpeckers, and Safety on the Water