LIMULUS POLYPHEMUS

The Atlantic horseshoe crab is scientifically known as Limulus Polyphemus. It is also known as American Horseshoe crab and it is a species of marine and brackish chelicerate arthropod.
Horseshoe is more related to the Ticks, Spiders, and crabs. These species are found in the Mexico Gulf and along to the Atlantic coast of North America.
Limulus polyphemus body consists of three fundamental parts: The head area, known as the ‘prosoma’, the stomach area or ‘opisthosoma’ and the spine-like tail or ‘telson’.
horseshoecrab
Source://daily.jstor.org
The tail of Horseshoe earns this order and Xiphosura Name. This name is derived from the greek “Sword Tail”. The males Limulus are smaller as compared to Female Limulus Polyphemus. The Carapace looks like a horseshoe and its color is from greenish grey to dark brown.
 
A large variety of marine species attached to the carapace, including molluscs, algae, flatworms, barnacles and bryozoans, and horseshoe crabs have been depicted as ‘living Museums’ because they support a number of organisms.
TypeDetail
NameAtlantic horseshoe crab
Scientific NameLimulus Polyphemus
SynonymsMonoculus Polyphemus Linnaeus

Vernacular Names

• English: common horseshoe crab
• Catalan: Cranc de ferradura atlàntica
• Czech: Atlantický podkovy krab
• Danish: Atlantic hestesko krabbe
• Dutch: Atlantische hoefijzerkrab
• Finnish: Atlantin hevosenkengän rapu
• French: Crabe des fèves de l’Atlantique
• Galician: Cangrejo de herradura atlántica
• German: Atlantischer Pfeilschwanzkrebs
• Greek: Ατλαντικό πέταλο καβούρι or Atlantikó pétalo kavoúri
• Hausa: Atlantic crawl crab
• Italian: Granchio a ferro di cavallo atlantico
• Japanese: 大西洋のカブトガニ
• Polish: Krab Atlantic podkowy
• Portuguese: Caranguejo-ferradura-do-atlântico
• Russian: Атлантический подковообразный краб or Atlanticheskiy podkovoobraznyy krab
• Spanish: Cangrejo de herradura atlántico
• Swedish: Atlantic hästsko krabba

History

The history of Limulus Polyphemus is given below:

Origin of Limulus Polyphemus

The Limulus Polyphemus or Horseshoe crab is a living fossil that is almost identical to this species, it is also said that the Triassic period was present 230 million years ago. Similar species were also present in the Devonian, a stunning 400 million years ago.
Regardless of their normal name, they are not crabs but rather are identified with the 8-legged creature (insects, scorpions, ticks, and parasites), They are the nearest living relatives of the extinct trilobites.

Fossil Records Of Limulus Polyphemus

Native Americans have eaten their eggs. yet today Atlantic horseshoe crabs are used as a fishing bait, in the biomedicine (particularly for Limulus amebocyte lysate) and science.
They also play a very important role in the local biological systems, with their eggs giving an essential nourishment source to shorebirds, the adults and the juveniles being eaten by ocean turtles.
The three other extant species in the family Limulidae are also known as horseshoe crabs but they are only restricted to the Asian region.
Limulus polyphemus is accepted to be the nearest living relative of trilobites (Shuster 1982). Such as chelicerates, members from the Order Xiphosurida have a two body section comprising of a prosoma, or head region; and an opisthosoma, or stomach region.
Ostrorepi
Source://cs.wikipedia.org
The prosoma contains have almost 6 pairs of legs, all of which bear paws aside from the last pair. The prosoma also contains 2 sorts of eyes: 2 ommatidia or compound eyes are situated on either side of the head; and 2 simple eyes, or ocelli, are situated in the focal point of the head.
 
The opisthosoma also contains an extra 6 sets of pairs that help in breath, locomotion, and reproduction. The abdominal appendages first pair form a genital operculum that houses the genital pores. The rest of the 5 sets of appendages are adjusted into a series of covering plates that work as gills.
The plate underside is highly folded like leaf-like folds or lamellae, This provides an actual surface for the gas exchange. Because of their morphology, the stomach plates have turned out to be known as book gills.

Distinctive Features Of Limulus Polyphemus

Horseshoe crabs are normally active at the night time. At the time of full moon, they are very active and at their peak. They burrow for nourishment, for example, molluscs, worms, and algae in the sediment. At the time of Summer and spring, the adult Horseshoe moves in huge numbers towards sandy beaches and the congregate in shallow water.
Their breeding is associated with the tidal and lunar cycles. The reason is most adults arrive at the time of full or new moon and they arrive just for a couple of hours with high tide. On the other hand, the direction of waves guides the female towards the beach.
Male horseshoe keeps watching from the base of the beach in the shallow water, holding up to intercept beach bound females. Pairs move toward the high tide and the male prepares the eggs as they are laid into 15 centimeters deep in the sand. It is estimated that around 2,000 to 20,000 eggs might be delivered in a single clutch.
 
Almost All the time there might be in excess of one male going with every female. In some cases, it is observed that there have been 14 Males attracted to one female. As the tide waves move back, the horseshoe crabs also move back to the ocean.
Around five weeks the sticky eggs hatch, However, this is dependent on the temperature. The larva, that is known as ‘trilobite’ may stay covered in the sand for various weeks before they start emerging in the high tide. After they enter the water, they experience a ‘swimming free for all’ of steady, enthusiastic action.
limulus polyphemus in water
Source://www.scubadiving.com
Six to eight days in the wake of developing, they shed into the primary adolescent stage, which is fundamentally the same as in appearance to the adult stage. At this stage, they stop swimming and start living at the bottom of the sea. Limulus Polyphemus have very slow growing, therefore, Males crabs reach sexual maturity at the age of 9 to 11 years.
On the other hand, Female Crabs reach their sexual maturity at the age of 10 to 11 years. The average lifespan of Horseshoe crabs is between 20 to 40 years.
The horseshoe crab is a very important part of the environment. Their eggs are the source of food for species like sea turtles, wading birds, fish, and alligators. Besides, the activity of the crab as it furrows the ocean bed looking for sustenance circulates air through the substrate, bringing about a more elevated amount of species richness.

Geo-Distribution

The Atlantic horseshoe crab is the main surviving (living) types of the horseshoe crab that is native to the Americas. The other extinct species are known just because of their fossil remains in the region.
The other species of horseshoe crab are restricted to Asia, however, all are very similar in shape and conduct. The Asian species are Tachypleus Gigas , Tachypleus tridentatus, and Carcinoscorpius rotundicauda.
In the Atlantic East Coast of the United States going from Maine to Florida Atlantic, horseshoe crabs are found. In the Gulf Coast of the United States, they are found in Alabama, Florida, Mississippi, and Louisiana. Outside the United States, Yucatan peninsula in Mexico is the other largest breeding area for Horseshoe crabs.
Limulus polyphemus is also found in almost three water of the Indian River Lagoon (Mosquito Lagoon, Banana River, Indian River ). A large number of horseshoe crabs is found in the India River Lagoon, southern Banana River, and southern Mosquito Lagoon.

Morphology

The morphology of the is described below Limulus Polyphemus is given below:

Eyes

Limulus eyes perceive the polarized light only.

Growth

Below the beach surface of 5 to 25cm the L.Polyphemus eggs develop. The Embryonic development is dependent on the temperature and location of the nests in the beach.

Reproduction

The first pair of six flap-like appendages on the underside of abdomen act like a cover for genital pore. The sperm or the egg are released through this pore.

Ecology of Limulus Polyphemus

The crab nourishes on annelid worms, mollusks, other benthic spineless creatures, and bits of fish. It is lacking jaws, therefore it crushes the food with bristles on its legs and a gizzard that contains sand and gravel.
 
The reproducing season Limulus polyphemus of differs. southern populaces (southern Florida and the Yucatán Peninsula) breed year-round. While Northern populaces (all in the United States, aside from those in southern Florida)breed from the spring to the Autumn time.

Food Habits

The L.polyphemus feed at night on small molluscs, worms, and algae. The food is picked by the chelicerae and it is passed back to bristle base where food is chewed.

Habitat

In the Atlantic East Coast of the United States going from Maine to Florida Atlantic, horseshoe crabs are found. In the Gulf Coast of the United States, they are found in Alabama, Florida, Mississippi, and Louisiana. Outside the United
States, Yucatan peninsula in Mexico is the other largest breeding area for Horseshoe crabs.
The Depth range is based on 921 specimens in 1 taxon. Water temperature and chemistry range is also given below.

Environmental ranges

  • Depth range (m): 0 – 303.5
  • Oxygen (ml/l): 3.840 – 6.494
  • Silicate (umol/l): 1.081 – 7.879
  • Salinity (PPS): 32.426 – 36.472
  • Temperature range (°C): 7.337 – 24.310
  • Phosphate (umol/l): 0.119 – 0.832
  • Nitrate (umol/L): 0.327 – 13.432

Life Span Of Limulus Polyphemus

Limulus Polyphemus have very slow growing, therefore, Males crabs reach sexual maturity at the age of 9 to 11 years. On the other hand, Female Crabs reach their sexual maturity at the age of 10 to 11 years. The average lifespan of Horseshoe crabs is between 20 to 40 years.

Taxonomy

Known Hazards

The number of inhabitants in horseshoe crabs has declined drastically. In the past, they were murdered in substantial numbers by shellfish diggers, as the species preys on mollusks.

They were also used for a food source for other animals. In the 30s somewhere in the range of four and five million people gathered this animal every year. At present they are collected in large numbers for use as eel and conch trap; in 1996 alone, Almost like two million horseshoe crabs were murdered consequently.

Horseshoe crabs have additionally been utilized broadly in the biomedical business for the make of surgical sutures, making dressings to consuming casualties, and in eye research.

Benefits

Polyphemus and its eggs are an essential segment of the IRL biological community, giving food to threatened loggerhead ocean turtles, swimming fowls, gators and numerous types of fish.
These species are very valuable for the medical research community and for medical testing. It is also used for the LAL (Limulus Amebocyte Lysate) test to detect the bacterial endotoxins in the pharmaceuticals.
 
The horseshoe crab blood Enzymes are also used by the astronauts in the international space station to test the surfaces that have unwanted fungi and bacteriaProtein from crab blood is also under investigation as the naval antibiotic.

Similar Species

Species that are similar to the Limulus Polyphemus are:
Ticks
Crabs

Limulus Polyphemus Fun Facts

Apart from all the hazards, there are also some fun facts about the Limulus Polyphemus:
Limulus Polyphemus Fun Facts

References

Awais Ahmed

Awais Ahmed

An IT(Information Technology) graduate from Bahria University Islamabad, I started my carrier as a Freelance in the year 2016 and have worked as a Blogger and Content Creator at various organizations. Currently working as a Content Creator at Tapedaily. Staying updated and writing research-based content related to Plants, Animals, and various kingdoms are my key interest.

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