Horseshoe Crab.pdf

The American horseshoe crab, Limulus Polyphemus, has been on Earth for millions of years and is often misunderstood. Despite its alien appearance, it is a harmless creature with 10 eyes, including the largest photoreceptors in the animal kingdom. Horseshoe crabs are related to spiders and scorpions, and there are only four species, with the American species found on the Atlantic coast from Maine to the Yucatan peninsula.

They are used as bait, their blood is drawn for pharmaceuticals, and they are ground up into fertilizer. The crabs migrate to Delaware Bay to mate and lay eggs, which are also a food source for hundreds of thousands of migrating shorebirds. The horseshoe crab population has been declining since the 1990s, and surveys are conducted to assess their health.

The crabs are predictable in their mating habits, preferring high tides during full or new moons. However, they are sensitive to wind and waves, and their spawning can be disrupted by strong weather conditions. During mating, females burrow into the sand and lay clusters of 4,000 eggs, which are then fertilized by the males.

The crabs take risks during mating, and many die on the beach after being flipped onto their backs by waves. Larger females tend to attract more males, and satellite males will arrange themselves at 45-degree angles around the female. Despite the challenges, the horseshoe crab remains a remarkable and fascinating creature, with a unique appearance and behavior.