Horseshoe Crab

Context:

Horseshoe crab populations have crashed with decreased spawning numbers in the Delaware Bay estuary.

• Environmental groups petitioned the U.S. government seeking endangered species protection for the American horseshoe crab, a “living fossil” under threat.

Horseshoe Crab:

• Regarded as a marine ‘living fossil’
• Name originates – From the rounded shape of the head, because just like the shoe on a horse’s foot, the head is round and U-shaped.
• More than 300 million years old, making them even older than dinosaurs.
• Looks like prehistoric crabs, but are more closely related to scorpions and spiders.
• Belongs to – Crustacean family
• Types –
  •  American horseshoe crab (Vulnerable)
  •  Tri-spine horseshoe crab (Endangered)
• Characteristic features –
  • Eyes and tail are used to find mates and determining movement and changes in moonlight.
  • It dines at night on worms and clams, and may also eat algae consuming them with appendages located in front of its mouth.
  • Because it has no mandible or teeth, the horseshoe crab crushes food between its legs before passing it to the mouth.
• Threats – Oil spill, Habitat loss

The Delaware Estuary:

• Location – United States
• Stretches – From the Trenton falls to the mouth of the Delaware Bay between Cape May and Cape Henlopen.
• The bay’s freshwater mixes for many miles with the saltwater of the Atlantic Ocean.
• A host to the 2^nd largest population of migrating shore birds in North America.
  • Migrating birds gain up to 50% of their body weight in fat by feasting on horseshoe crab eggs and submerged vegetation.
• Home to the world’s largest horseshoe crab population
• Supports –
  • Critical habitat for 35% of the region’s threatened and endangered species.
  • The world’s largest freshwater port (Port of Philadelphia)
  • 2^nd  largest refining petrochemical center in the U.S

Source: The Hindu

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Previous Year Question

Among the following organisms, which one does not belong to the class of other three?

[UPSC Civil Services Exam – 2014 Prelims]

(a) Crab
(b) Mite
(c) Scorpion
(d) Spider

Answer: (a)

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