Morphology of a limulus (horseshoe crab): marine arthopod which lives near the shore.
Frontal organ: organ of the horseshoe crab situated at face-level.
Chelicera: a pair of venomous hooks situated on the head of a horseshoe crab.
Walking leg: floating appendage.
Genital operculum: structure covering the opening to the genital organs.
Transverse auricular groove: shallow impression related to the ear.
Appendages modified to serve as gills: leaf-shaped leg.
Auricular cavity of the tail spine: cavity related to the flexibility and movement of the telson.
Telson (tail spine): barb at the end of the horseshoe crabs tail.
Abdomen: posterior part of the body of a horseshoe crab.
Mobile spine: movable tail of the horseshoe crab.
Cephalothorax: head and thorax of the horseshoe crab, which together form one section of the body.
Eye: sight organ of a horseshoe crab.
Ocelli: rudimentary eye.

Animation : Horseshoe crabs - sea spiders

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