Horseshoe crabs

http://www.pbs.org/wnet/nature/crash-a-tale-of-two-species-the-benefits-of-blue-blood/595/

Horseshoe crabs Limulus polyphemus

The Horseshoe crabs belongs to Limulidae family.  

They possess a strong exoskeleton, ten legs, long tail and spines. It has three sections: 
1. Head (prosoma), largest section and houses some of the vital organs, heart, brain, nervous system and glands. There are nine eyes, two for finding a mate and seven are light receptors. 
2. Abdomen (opisthosoma), they have spines in the centre, they aid in protection, the muscles are used in breathing and movement.
3. Tail (telson), the tail is large but it doesn't pose a threat. 

They males are smaller than the females and range from fourteen to nineteen inches. They can live for twenty years.  They feed on clams and worms.  The eggs are laid by the females on the beaches in the summer.  They can be found near beaches.  They communicate by pheromones. 

The females arrive at the breeding ground after the males, the females let the pheromones go to get the males attention. The males hold onto the females and walk to the shore. The females dig the nest and put the eggs in the hole. 

Nwf.org, (2015). Horseshoe Crab - National Wildlife Federation. [online] Available at: http://www.nwf.org/wildlife/wildlife-library/invertebrates/horseshoe-crab.aspx [Accessed 15 Apr. 2015].