Arthropod and Horseshoe crab

Arthropod noun - Invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin.

Horseshoe crab and arthropod are semantically related. In some cases you can replace phrase "Horseshoe crab" with "Arthropod", this terms are similar.

Horseshoe crab noun - Large marine arthropod of the Atlantic coast of North America having a domed carapace that is shaped like a horseshoe and a stiff pointed tail; a living fossil related to the wood louse.

Arthropod and horseshoe crab are semantically related. You can use "Arthropod" instead a noun phrase "Horseshoe crab".