DOCSLIB.ORG

A Valuable Marine Creature

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Valuable Marine Creature R&D Horseshoe Crab – A Valuable Marine Creature by Anil Chatterji and Noraznawati Ismail The ancestors of the horseshoe crab crabs, these five pairs are highly University Malaysia Terengganu are believed to have inhabited brackish specialized appendages with broad, flat or freshwater environments. Fossil and overlapping plates. The external The ocean is a treasure trove of many records show that the oldest horseshoe gills of the horseshoe crab were partly living and non living resources. About 26 crabs were similar to the aglaspids, with developed from these appendages. phyla of marine organisms are found in less abdominal segments but without the ocean, whereas arthropods (jointed well defined appendages. The five pairs Horseshoe crab habitat limbs and an outer shell, which the of walking legs, discontinuing at the The horseshoe crab belongs to the animals moult as they grow), with over abdomen, were present in the primitive benthic community. They prefer calm 35,000 varieties, contribute four-fifth of forms. Gradually, the first four pairs seas or estuaries with muddy sandy all marine animal species. Surprisingly, a started developing pinching claws, bottoms for their biogenic activities. They number of marine organisms, suspected whereas, the last pair terminated in migrate to the shore from the deeper to be extinct, still flourish as living primitive spines. In modern horseshoe waters specifically for breeding purposes. animals. The horseshoe crab, a chelicerate During this shoreward migration the arthropod, is one such amazing creature animal is subjected to a wide range of and is considered to be the oldest 'living environmental conditions including fossil'. salinity and temperature. Although The horseshoe crab has descended detailed knowledge of the complete life from mud dwelling primitive arthropods, cycle of the animal is not yet known, named trilobites, which lived in the it is generally believed that the animal Precambrian seas, nearly 600 million inhabits the deeper zone of the sea for years ago. After 150 million years or most parts of its life. The fluctuating so, the horseshoe crab evolved into its habitats encountered by the horseshoe present shape and, surprisingly,the crab during their different stages of life archeal animal body has not shown any reflect their amazing ability to tolerate phenotypic change, even after a span of and adapt to different environmental 350 million years. While so many animals, conditions. including dinosaurs and many other The horseshoe crab has a patchy latecomers to the Mesozoic era, have distribution pattern. They have highly become completely extinct, it is a wonder specialized methods for detecting how the humble horseshoe crab has their selected habitat for reproduction survived for such a long period. It seems and dispersal. These methods ensure that this animal can overcome all kinds the animals their safe arrival to their of adverse situations in its estuarine and respective destinations and reduce coastal shallow habitat. It can also tolerate the chance of mortality during their wide ranges of salinity, temperature, migration. Such characteristics could desiccation and submergence. possibly contribute to the evolutionary 50 | Prospect Malaysia R&D T. gigas migrating on sandy beaches for spawning advantage of the horseshoe crab for their of the horseshoe crab, Limulus and namely Carcinoscorpius rotundicauda, very long survival. Cancer mollucensis were reported from Tachypleus gigas and Tachypleus In contrast, uniformly distributed the same region. tridentatus along the coast of Malaysia. animals are subject to more competition The diversified Paleozoic group is A record breaking large specimen of a for their biological needs and have fewer represented by only four species with T. tridentatus (7.5 kg) was collected for opportunities to survive. The horseshoe confirmed discernible morphology the first time along the coast of Paper crab has a difficult distribution pattern and three genera of the horseshoe Sabah. Although there are high degrees because the animal is totally dependent crab worldwide. It is interesting to of similarity among all three Asian on two important physical stimuli – the note that among these four species, species of the horseshoe crab, T. gigas is tide and the lunar periodicities. There Limulus polyphemus and Tachypleus morphologically more closely related to have been a number of attempts to study tridentatus occur in a north-south-north T. tridentatus than C. rotundicauda. the distribution of the horseshoe crab in direction, whereas, Tachypleus gigas and the recent past decades. For example, the Carcinoscorpius rotundicauda occur in Optic nerves occurrence of a species of the horseshoe an east-west-east direction (Plate 4). This Modern researchers find the crab, Tachypleus hoeveni, was reported includes Malaysia. It is an interesting horseshoe crabs’ unique physiology for the first time off the coast of Moluccas. phenomenon to have an abundance of the heart and the functioning of its Later, the occurrence of two more species of three species of the horseshoe crab, optic nerves interesting. The crab has altogether ten eyes which are located on the upper surface of the body. Out of these, two pairs are known as true eyes though the rest of the organs are also sensitive to light. The compound eyes of the horseshoe crab can polarize light and the crystal lining cones can concentrate it tenfold. This is an adaptation for their continuous living in translucent and dark muddy waters. The vision is also sensitive to infrared and ultraviolet lights. These structures help the horseshoe crabs to find their way on cloudy days when the sun is not visible - a small patch of clear sky is enough for the animal to locate the sun. This principle has been useful in developing a compass for navigation in the Polar Regions where magnetic compasses are not reliable and celestial navigation is also difficult as the sun and stars are not visible in the long polar twilight. The design of eye structure of the horseshoe crab has also been successfully adopted in designing solar energy collectors. The optic nerve cells of the horseshoe crab are cross connected in such a way that when one nerve is stimulated, its partner nerve gets inhibited, resulting in an increase in rotundicauda in a mangrove area contrast of the images. Prospect Malaysia | 51 water. A student of UMT working on a horseshoe crab In China, people use the big carapace of the T. tridentatus species as a hat R&D or ladle. They also use the tail of the horseshoe crab to make small ornaments. In Korea, fishermen sell hundreds of dried horseshoe crab shells as decorative pieces to tourists. In Singapore, Malaysia, and Borneo, the eggs of horseshoe crab are regarded a delicacy while people in the southern part of China blend the meat of the appendages with sauces and eat it as part of everyday food. Pregnant women in Singapore are said to eat the egg mass of the horseshoe crab for immunity for their foetus. Diagnosing endotoxins The blood of the horseshoe crab is generally known as haemolymph which is white in colour but it turns blue when In 1967, Prof H K Hartline of USA it was used as fertilizer for their fields exposed to air. Hence, horseshoe crabs shared a Nobel Prize for his notable work and ponds. In India, some of the tribes are also known as blue blooded animals. on the functioning of the optic nerves inhabiting the north-east coast of Orissa The blue colour of the blood is attributed of the horseshoe crab. A video system still use the tail piece for relief from to haemocyanin, a copper based molecule based on this principle was developed different types of pain. They tie the tail on that carries oxygen via the circulatory by General Electrical Company USA to their arms or prick their foreheads with system of the crab. The white blood provide sharper television images and is it. It has been reported that the tail tips cells of horseshoe crabs are known as presently in common use. The principle are used for healing arthritis or other joint amoebocytes which are elliptical in shape has also helped in developing improved pains and they are sold by faith healers and with a prominent nucleus. The radar systems. in West Bengal, India. It is believed that cytoplasm in the blood cells is densely Indians in the early days used to eat packed with large refractile granules Remedies and ornaments the appendages of the horseshoe crab. consisting of elements required for blood clotting. The blood cells aggregate For the past several decades, the Additionally, the dead carapace of the quickly when exposed to minute amounts horseshoe crab has had many uses for crab is boiled with mustard oil and used of endotoxins or harmful bacteria. humans. It is believed that the early for treating rheumatic pain in India. The In the presence of harmful bacteria, Indians used the tail spines of the crab Indians also used the hard carapace as the amoebocyte shape changes and, as spear tips. After grinding the body, a utensil for eating food and drinking The largest specimen of a horseshoe crab ever reported 52 | Prospect Malaysia R&D TACHYPLEUS LIMULUS POLYPHEMUS TRIDENTATUS (MULLER) (POCOCK) Atlantic Coast of North Western & Southern Japan, America from Maine to Taiwan, Philiphines & Yucatan North Borneo, Malaysia TACHYPLEUS GIGAS CARCINOSCORPIUS (MULLER) ROTUNDICAUDA (LATREILLE) Bay of Bengal (North - East Coast), Thailand, Malaysia, Bay of Bengal, Thailand, Philiphines, Borneo & Malaysia, Philiphines, Torres Straits Borneo & Torres Straits. simultaneously, long processes extend of endotoxins. This process is popularly from one amoebocyte to the other and The LAL test known as Limulus Amoebocyte Lysate appear in a pseudopod-like fashion. In human beings, the presence of or LAL test. Dr R Nandan, an Indian This process is followed by the these endotoxins is generally assessed scientist based in USA, was the first to degranulation of the amoebocyte and with the help of a rabbit vaccine test.
Load more

Recommended publications
  • The ′Crab′ That Might Have Saved Your Life
    Advertisement TOP STORIES / ENVIRONMENT / GLOBAL IDEAS GLOBAL IDEAS The 'crab' that might have saved your life Closely related to the spider and around since long before the dinosaurs, the horseshoe crab has light blue blood that's vital for medical research. But can these living fossils survive the age of man? In the waters along the eastern seaboards of the United States and several East Asian countries, lives a species so dogged in its determination to defy decimation, it's earned the tag of "living fossil." "They crawled underneath the legs of dinosaurs and the dinosaurs were on earth for 150 million years," said John Tanacredi, a professor at Molloy College in New York and an eminent authority on horseshoe crabs, which could be the most amazing species many people have never heard of. "Of course, the mass extinction event 65 million years ago that saw the demise of the dinosaurs — both terrestrial and in the marine environment — makes it even more unique that these animals have survived." More on dinosaurs: Dinosaurs are extinct because an asteroid hit the wrong spot Technically, they're not crabs, nor are they shaped like a horseshoe, exactly. Like crabs though, they're arthropods, but the four different species of the animal belong to the subphylum chelicerata, and so are closely related to arachnids such as spiders. The animals have an almost alien quality to their appearance. They grow to about 60 centimeters (23 inches) in length have hard, helmet-like outer shells, five pairs of legs with a mouth located at their center, and several pairs of eyes distributed across their bodies.
    [Show full text]
  • Population Structure and Breeding Pattern of the Mangrove Horseshoe Crab Carcinoscorpius Rotundicauda in Singapore
    Vol. 8: 61–69, 2009 AQUATIC BIOLOGY Published online December 29 doi: 10.3354/ab00206 Aquat Biol OPENPEN ACCESSCCESS Population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore Lesley Cartwright-Taylor*, Julian Lee, Chia Chi Hsu Nature Society of Singapore (NSS), 510 Geylang Road, #02-05 The Sunflower, Singapore 389466 ABSTRACT: The first year-long survey of the mangrove horseshoe crab Carcinoscorpius rotundi- cauda was conducted at the Mandai mudflats at Kranji in Singapore to determine if breeding is year round or seasonal and to provide qualitative and quantitative baseline data to monitor the health of the population. At spring tide from September 2007 to July 2008, volunteers collected horseshoe crabs along the exposed mudflats as the tide receded. The carapace width was measured, and the sex and breeding status of each individual were determined. The proportion of juveniles in different size groups varied in each month. In November and January, 25 and 30%, respectively, were 2 to 3 cm in width, while in June and July, 8 and 4%, respectively, were in this size group. The size cohorts showed recruitment to the smallest size classes from November to March and recruitment to the larger size classes from March to July. Juveniles less than 2 cm were not found in June, suggesting that there may be a rest period of low or no breeding activity from May to July resulting in none of the smallest sizes mid-year. Ratios of males to females varied from 0.85 to 1.78 throughout the year, and although pairs in amplexus were found year round, no spawning activity was seen.
    [Show full text]
  • Segmentation and Tagmosis in Chelicerata
    Arthropod Structure & Development 46 (2017) 395e418 Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd Segmentation and tagmosis in Chelicerata * Jason A. Dunlop a, , James C. Lamsdell b a Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, D-10115 Berlin, Germany b American Museum of Natural History, Division of Paleontology, Central Park West at 79th St, New York, NY 10024, USA article info abstract Article history: Patterns of segmentation and tagmosis are reviewed for Chelicerata. Depending on the outgroup, che- Received 4 April 2016 licerate origins are either among taxa with an anterior tagma of six somites, or taxa in which the ap- Accepted 18 May 2016 pendages of somite I became increasingly raptorial. All Chelicerata have appendage I as a chelate or Available online 21 June 2016 clasp-knife chelicera. The basic trend has obviously been to consolidate food-gathering and walking limbs as a prosoma and respiratory appendages on the opisthosoma. However, the boundary of the Keywords: prosoma is debatable in that some taxa have functionally incorporated somite VII and/or its appendages Arthropoda into the prosoma. Euchelicerata can be defined on having plate-like opisthosomal appendages, further Chelicerata fi Tagmosis modi ed within Arachnida. Total somite counts for Chelicerata range from a maximum of nineteen in Prosoma groups like Scorpiones and the extinct Eurypterida down to seven in modern Pycnogonida. Mites may Opisthosoma also show reduced somite counts, but reconstructing segmentation in these animals remains chal- lenging. Several innovations relating to tagmosis or the appendages borne on particular somites are summarised here as putative apomorphies of individual higher taxa.
    [Show full text]
  • Geological History and Phylogeny of Chelicerata
    Arthropod Structure & Development 39 (2010) 124–142 Contents lists available at ScienceDirect Arthropod Structure & Development journal homepage: www.elsevier.com/locate/asd Review Article Geological history and phylogeny of Chelicerata Jason A. Dunlop* Museum fu¨r Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, Invalidenstraße 43, D-10115 Berlin, Germany article info abstract Article history: Chelicerata probably appeared during the Cambrian period. Their precise origins remain unclear, but may Received 1 December 2009 lie among the so-called great appendage arthropods. By the late Cambrian there is evidence for both Accepted 13 January 2010 Pycnogonida and Euchelicerata. Relationships between the principal euchelicerate lineages are unre- solved, but Xiphosura, Eurypterida and Chasmataspidida (the last two extinct), are all known as body Keywords: fossils from the Ordovician. The fourth group, Arachnida, was found monophyletic in most recent studies. Arachnida Arachnids are known unequivocally from the Silurian (a putative Ordovician mite remains controversial), Fossil record and the balance of evidence favours a common, terrestrial ancestor. Recent work recognises four prin- Phylogeny Evolutionary tree cipal arachnid clades: Stethostomata, Haplocnemata, Acaromorpha and Pantetrapulmonata, of which the pantetrapulmonates (spiders and their relatives) are probably the most robust grouping. Stethostomata includes Scorpiones (Silurian–Recent) and Opiliones (Devonian–Recent), while
    [Show full text]
  • Arthropod Phylogeny Based on Eight Molecular Loci and Morphology
    letters to nature melanogaster (U37541), mosquito Anopheles quadrimaculatus (L04272), mosquito arthropods revealed by the expression pattern of Hox genes in a spider. Proc. Natl Acad. Sci. USA 95, Anopheles gambiae (L20934), med¯y Ceratitis capitata (CCA242872), Cochliomyia homi- 10665±10670 (1998). nivorax (AF260826), locust Locusta migratoria (X80245), honey bee Apis mellifera 24. Thompson, J. D., Higgins, D. G. & Gibson, T. J. CLUSTALW: Improving the sensitivity of progressive (L06178), brine shrimp Artemia franciscana (X69067), water ¯ea Daphnia pulex multiple sequence alignment through sequence weighting, position-speci®c gap penalties and weight (AF117817), shrimp Penaeus monodon (AF217843), hermit crab Pagurus longicarpus matrix choice. Nucleic Acids Res. 22, 4673±4680 (1994). (AF150756), horseshoe crab Limulus polyphemus (AF216203), tick Ixodes hexagonus 25. Foster, P. G. & Hickey, D. A. Compositional bias may affect both DNA-based and protein-based (AF081828), tick Rhipicephalus sanguineus (AF081829). For outgroup comparison, phylogenetic reconstructions. J. Mol. Evol. 48, 284±290 (1999). sequences were retrieved for the annelid Lumbricus terrestris (U24570), the mollusc 26. Castresana, J. Selection of conserved blocks from multiple alignments for their use in phylogenetic Katharina tunicata (U09810), the nematodes Caenorhabditis elegans (X54252), Ascaris analysis. Mol. Biol. Evol. 17, 540±552 (2000). suum (X54253), Trichinella spiralis (AF293969) and Onchocerca volvulus (AF015193), and 27. Muse, S. V. & Kosakovsky Pond, S. L. Hy-Phy 0.7 b (North Carolina State Univ., Raleigh, 2000). the vertebrate species Homo sapiens (J01415) and Xenopus laevis (M10217). Additional 28. Strimmer, K. & von Haeseler, A. Quartet puzzlingÐa quartet maximum-likelihood method for sequences were analysed for gene arrangements: Boophilus microplus (AF110613), Euhadra reconstructing tree topologies.
    [Show full text]
  • Valloisella Lievinensis RACHEBOEUF, 1992 (Chelicerata; Xiphosura) from the Westphalian B of England
    N.Jb. Geol. Palaont. Mh. 1995, H. 11 647-658 Stuttgart, Nov. 1995 Valloisella lievinensis RACHEBOEUF, 1992 (Chelicerata; Xiphosura) from the Westphalian B of England By Lyall I. Anderson and Carl Horrocks, Manchester With 3 figures in the text ANDERSON, L. I. & HORROCKS, C. (1995): Valloisella lievinensis RACHEBOUEF, 1992 (Chelicerata; Xiphosura) from the Westphalian B of England. - N. Jb. Geol. Palaont. Mh., 1995 (11): 647-658; Stuttgart. Abstract: Two small xiphosurans are described from geographically separate Westphalian B sites in England and assigned to Valloisella lievinensis RACHEBOEUF, 1992. Valloisella is removed from Euproopidae ELLER, 1938 and placed in Paleoli- mulidae RAYMOND, 1944. Zusammenfassung: Zwei kleine Xiphosuren aus geographisch getrennten Fundorten in England (Alter: Westfal B) werden beschrieben und der Art Valloi­ sella lievinensis RACHEBOEUF 1992 zugeordnet. Valloisella wird von den Euproo­ pidae ELLER, 1938 in die Paleolimulidae RAYMOND, 1994 iibertragen. Introduction Dix &JONES (1932) reported a small arthropod from the roof shales of the Little Vein coal in the lower part of the A. pulchra zone (Westphalian B) from Blaina Colliery, Pantyffynon, South Wales. The specimen was illustrated by way of a line drawing and was reported to have been deposited in the collections of the University College of Swansea under the acquisition number A. 152. The arthropod was found associated with non-marine bivalves and the other, more commonly encountered, Coal Measures xiphosuran, Bellinurus PICTET, 1846. The tripartite division of the fossil into a prosoma, opisthosoma and tail spine led Dix & JONES (1932) to compare their specimen with the extant xiphosuran Limulus polyphemus. They concluded that it was a post-larval, but immature, stage of an aquatic chelicerate but did not formally assign it a name.
    [Show full text]
  • Horseshoe Crabs (Limulus Polyphemus)
    Horseshoe Crabs (Limulus polyphemus) Although Delaware Bay is famous for horseshoe crabs, the New York-New Jersey Harbor Estuary should not be overlooked when it comes to this animal. During the full moon in May or June, Horseshoe Crabs can be seen mating on the Estuary’s sandy beaches including Sandy Hook Bay, Raritan Bay, Caven Point Beach in Jersey City, along Lower New York Harbor, in Staten Island’s Great Kills and along Jamaica Bay. The current range of the Atlantic Coast Horseshoe Crab goes from Maine to the Yucatan Peninsula and the Gulf of Mexico. They are most abundant from Virginia to New York. Other than that, this particular species (Limulus polyphemus) is found nowhere else in the world. Horseshoe Crabs live in different habitats during their various life stages. During mating season, mature Horseshoe Crabs move from offshore to the Estuary’s sandy beaches where they take shelter from harsh ocean winds and waves. The female Horseshoe Crab digs a series of shallow holes on these calm beaches, depositing up to 20,000 pearl-sized, blue-green eggs per hole. Then males, using specialized claws called pedipalps, attach to the back of the female’s shell to be dragged over the nests to fertilize them. A very small percentage of eggs hatch into larvae in 4-30 days at a similar high tide. These escape into the Estuary. Most eggs and even larvae serve as food for migrating shorebirds and other animals. The preferred habitat for juvenile horseshoe crabs is the shallow water of the Estuary’s bays.
    [Show full text]
  • Unlocking the Mysteries to Early Life on Earth
    Unlocking the mysteries to early life on Earth thestarphoenix.com/life/bridges/unlocking-the-mysteries-to-early-life-on-earth Bob Florence More from Bob Florence 12/9/2016 Michael Cuggy likes reading mysteries. He could write one. A true story is happening before his eyes. Cuggy is a science lab co-ordinator at the University of Saskatchewan. Schooled in zoology, on staff in geology, he brings the blood and buzz of biology to the study of fossils. For almost a decade he has travelled to north central Manitoba to do field work. Using a hammer and chisel he breaks rock, looking for signs of ancient life. “It’s very rewarding and very frustrating,” he said. “Some days you find crazy things, some days nothing.” Those are the quirks of doing a cold case half a billion years old. Before North America was a continent — before animals, before plants and trees, before land plates shifted — the area that is now the Grand Rapids Uplands in Manitoba was located near the equator. The Earth’s temperature was higher. There was less oxygen. Volcanos stewed. The world was different. But as Cuggy is showing, life brewed. Cuggy does field work in the Uplands with Dave Rudkin, who is the assistant curator of paleontology at the Royal Ontario Museum in Toronto, and Graham Young, the fossil foreman at the Manitoba Museum in Winnipeg. They scrape rock. They clean rock. By finding bits and pieces of organisms embossed in stone, they fill in the blanks from Earth’s past. History has currency. The rarer the fossil, the deeper the intrigue.
    [Show full text]
  • Limulus Polyphemus
    Horseshoe Crab − Limulus polyphemus Overall Vulnerability Rank = Very High Biological Sensitivity = High Climate Exposure = Very High Data Quality = 92% of scores ≥ 2 Expert Data Expert Scores Plots Limulus polyphemus Scores Quality (Portion by Category) Low Moderate Stock Status 2.0 2.8 High Other Stressors 2.4 2.2 Very High Population Growth Rate 3.4 2.6 Spawning Cycle 2.8 3.0 Complexity in Reproduction 3.1 2.8 Early Life History Requirements 2.0 3.0 Sensitivity to Ocean Acidification 2.1 2.6 Prey Specialization 2.2 2.4 Habitat Specialization 2.3 2.8 Sensitivity attributes Sensitivity to Temperature 2.1 3.0 Adult Mobility 2.6 2.8 Dispersal & Early Life History 2.9 3.0 Sensitivity Score High Sea Surface Temperature 3.9 3.0 Variability in Sea Surface Temperature 1.0 3.0 Salinity 2.4 3.0 Variability Salinity 1.2 3.0 Air Temperature 3.1 3.0 Variability Air Temperature 1.0 3.0 Precipitation 1.3 3.0 Variability in Precipitation 1.4 3.0 Ocean Acidification 4.0 2.0 Exposure variables Variability in Ocean Acidification 1.0 2.2 Currents 2.0 1.0 Sea Level Rise 3.6 1.5 Exposure Score Very High Overall Vulnerability Rank Very High Horseshoe Crab (Limulus polyphemus) Overall Climate Vulnerability Rank: Very High (83% certainty from bootstrap analysis). Climate Exposure: Very High. Three exposure factors contributed to this score: Ocean Surface Temperature (3.9), Ocean Acidification (4.0) and Sea Level Rise (3.6). Horseshoe Crabs use marine habitats, but spawn in intertidal areas that could be impacted by sea-level rise.
    [Show full text]
  • The Horseshoe Crab and the Red Knot
    The Horseshoe Crab and the Red Knot The horseshoe crab and the red knot each have amazing, yet inseparable stories. They are an example of the interdependence of two creatures and their importance in the environment. Both are losing habitat and both populations are declining. The decline of the red knot was noticed first, which led to the discovery that the horseshoe crab was declining, too. Horseshoe Crab The horseshoe crab is often called a “living fossil” because it has remained unchanged for 450 million years. Today, four species of horseshoe crab roam coastal waters of the globe. The species commonly found in North America is the Atlantic horseshoe crab (Limulus polyphemus). The Atlantic horseshoe crab can be found along the North American coast from the Yucatan peninsula to Maine. The horseshoe crab is not a crab at all. They are more closely related to spiders, ticks and scorpions, which are all arachnids. Horseshoe crabs are invertebrates with hard, protective exoskeletons on the outside of their bodies. Horseshoe crabs have five pairs of feet that have spiny bristles near the base. These bristles are used to chew food, like clams and marine worms, by moving their legs. They have a spike-shaped tail, called a telson, that they use to flip themselves over if they get stuck on their backs. As they grow, horseshoe crabs must shed, or molt their exoskeleton. Horseshoe crabs have multiple pairs of eyes on the top and underside of their bodies. Unlike ours, horseshoe crab blood is blue. This blue coloration is caused by the copper in their blood, which they use as an oxygen-carrying molecule.
    [Show full text]
  • Horseshoe Crabs
    Species Profile: Profile: HorseshoeAtlantic CrabSturgeon Bait, Birds and Biomedical: A Glimpse into the World of Species Snapshot Horseshoe Crabs Introduction Horseshoe Horseshoe crabs provide the backdrop for one of the most interesting marine resource management issues along the Atlantic coast. An ecologically important species, horseshoe Crab Limulus polyphemus crab eggs are a primary food source for red knots, a shorebird that is near threatened under the Endangered Species Act (ESA), as they pass through the Delaware Bay on their Taxonomy: long migration from South America to the Arctic. Also economically important, horseshoe • Horseshoe crabs are in the taxonomic class crabs provide bait for commercial American eel and conch fisheries along the coast. Their Merostomata, which means "legs attached to bright blue blood is also used by the biomedical industry to produce Limulus Amoebocyte mouth" Lysate (LAL), an important tool for detecting contaminants in medical devices and drugs. • Their scientific name “polyphemus” alludes to a The challenge for fisheries managers is to ensure that horseshoe crabs are managed to one-eyed giant in Greek mythology, due to the meet all these diverse needs, while conserving the resource for future generations. fact that people thought they only had one eye (they actually have ten). Life History Horseshoe crabs are a marine arthropod found along the Atlantic coast from northern Interesting Facts Maine to the Yucatan Peninsula and the Gulf of Mexico. Adults either remain in estuaries • Horseshoe crabs have existed for nearly 450 or migrate to the continental shelf during the winter months. Migrations resume in the million years, predating flying insects, dinosaurs spring when the horseshoe crabs move to beach areas to spawn.
    [Show full text]
  • Exocuticular Hyaline Layer of Sea Scorpions and Horseshoe Crabs Suggests Cuticular Fluorescence Is Plesiomorphic in Chelicerates
    Journal of Zoology. Print ISSN 0952-8369 Exocuticular hyaline layer of sea scorpions and horseshoe crabs suggests cuticular fluorescence is plesiomorphic in chelicerates M. Rubin1,2,3, J. C. Lamsdell2,4 , L. Prendini3 & M. J. Hopkins2 1 Department of Geology, Oberlin College, Oberlin, OH, USA 2 Division of Paleontology, American Museum of Natural History, New York, NY, USA 3 Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA 4 Department of Geology and Geography, West Virginia University, Morgantown, WV, USA Keywords Abstract cuticle; ultraviolet light; fluorescence; Chelicerata; histology; scanning electron microscopy; The cuticle of scorpions (Chelicerata: Arachnida) fluoresces under long-wave ultra- Xiphosura; Scorpiones. violet (UV) light due to the presence of beta-carboline and 7-hydroxy-4-methylcou- marin in the hyaline layer of the exocuticle. The adaptive significance of cuticular Correspondence UV fluorescence in scorpions is debated. Although several other chelicerate orders James C. Lamsdell, Department of Geology and (e.g. Opiliones and Solifugae) have been reported to fluoresce on exposure to UV Geography, West Virginia University, 98 light, the prevalence of cuticular UV fluorescence has not been confirmed beyond Beechurst Avenue, Brooks Hall, Morgantown, scorpions. A systematic study of living chelicerates revealed that UV fluorescence WV 26506, USA. of the unsclerotized integument is ubiquitous across Chelicerata, whereas only scor- Email: [email protected] pions and horseshoe crabs (Xiphosura) exhibit cuticular UV fluorescence. Scanning electron microscopy and histological sectioning confirmed the presence of a hyaline Editor: Gabriele Uhl layer in taxa exhibiting cuticular fluorescence. The hyaline layer is absent in all other chelicerates except sea scorpions (Eurypterida) in which a taphonomically Received 7 November 2016; revised 21 June altered hyaline layer, that may have fluoresced under UV light, was observed in 2017; accepted 28 June 2017 exceptionally preserved cuticle.
    [Show full text]