Horseshoe Crabs

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Context

• The Zoological Survey of India (ZSI) and the Odisha Forest Department have joined hands to tag horseshoe crabs along the State’s coast for its conservation and management.

Background and Details

Dwindling Horseshoe Population: Threats

• Horseshoe crabs are one of oldest living creatures on the Earth, and a valuable species medicinally.
• There are reports of a dwindling population of horseshoe crabs along the Odisha coast.
• Destructive fishing practices are major threats to horseshoe crabs, and there are reports of illegal smuggling of the species from the Odisha and West Bengal coasts.
• Though the crab is not consumed by people, its death is primary caused by fishing nets.

The initiative of affixing tag

• Hence, scientists are affixing tag, the first such effort in the country.
• The first tagging of horseshoe crabs was carried out in the Khandiamuhan estuary of the Balasore coast.
• The plan involves tagging hundreds of crabs to determine their population pattern, and threats to them.
• Significance: The collaboration could result in the identification of stretches along Odisha where destructive standing fishing nets could be prohibited.

About Horseshoe Crab

• Horseshoe crabs have been around for more than 300 million years, making them even older than dinosaurs.
• The horseshoe crab is one of oldest living creatures to have lived millions of years without undergoing any morphological change and it’s known for its strong immune system.
• Horseshoe crabs are arthropods of the family Limulidae and are the only surviving xiphosurans.
• Despite their name, they are not true crabs or crustaceans.
• Rather, they are chelicerates: one of the major subdivisions of the phylum Arthropoda.
• Horseshoe crabs have changed little in appearance since they first evolved in the Triassic, earning them the title of "living fossil".

Horseshoe Crab species

• Only four species of horseshoe crab are alive today. These are:
• Limulus polyphemus (1), which is found along the eastern coast of North and Central America, and
• three Indo-Pacific species, Tachypleus gigas (4), Tachypleus tridentatus (3) and Carcinoscorpius rotundicauda .

Habitat

• Most are marine, though the mangrove horseshoe crab is often found in brackish water.
• Additionally, certain extinct species transitioned to living in freshwater.
• Horseshoe crabs are primarily benthic animals but can swim if needed.

Use in Medical Industry

• Horseshoe crabs are often caught for their blood, something valuable to the medical industry. The blood's usefulness comes from the Limulus amebocyte lysate, a chemical used to detect bacterial endotoxins.
• The blood of horseshoe crabs is very important for the preparation of rapid diagnostic reagents. All injectables and medicines are tested with the help of horseshoe crabs.

Species in India

• India is home to two species of horseshoe crabs — Tachypleus gigas and Carcinoscorpius rotundicauda (mangrove) — and both the species are found along the northeastern coast of India, especially along the Odisha and West Bengal coast.
• While Odisha has both Tachypleus gigas and Carcinoscorpius rotundicauda, the Carcinoscorpius rotundicauda are seen in the Sundarbans mangroves of West Bengal.

Conservation Status

• The American horseshoe crab (Limulus polyphemus) is listed as Vulnerable, there are three Asian species, the tri-spine horseshoe crab (Tachypleus tridentatus) is Endangered, the coastal horseshoe crab (T. gigas) and mangrove horseshoe crab (Carcinoscorpius rotundicauda), are listed as Data Deficient.
• Horseshoe crabs are a Schedule 2 species under the Wildlife Protection Act, 1972.

Need for Conservation efforts

• Illegal trade in horseshoe crabs has to be curbed.
• Odisha State Wildlife Advisory Board urged the Union Ministry of Environment, Forest and Climate Change to place horseshoe crabs on the list of marine species requiring the development of a Species Recovery Plan.

SOURCE: THE HINDU