astronomy-to-zoology:

“Hunchback Amphipod” (Iphemedia gibba)

…a strikingly marked  blue and yellow species of Gammarid amphipod that is known to occur along the coast of South Africa, ranging from the Cape Peninsula to Port Elizabeth. Hunchback amphipods are often encountered from the subtidal zone down to at least 25 meters (82 feet), where it often seen near sessile invertebrates like sponges or corals. 

Classification

Animalia-Arthropoda-Crustacea-Malacostraca-Amphipoda-Gammaridea-Iphimediidae-Iphimedia-I. gibba

Image: seascapeza