Malacostracans are invertebrates that include crabs, lobster, crayfish, shrimp, and amphipods, with an estimated 40,000 living species. The Class Malacostraca around 510 million years ago (+/- 30 million years), based on current evidence. Characteristics of Malacostracans generally include 20-21 body segments divided among a head, a thorax, and an abdomen.
Kingdom: Animalia
-Phylum: Arthropoda
–Class: Malacostraca
I have photographs only two Malacostracans so far:
–Marbled Crab (Pachygrapsus maroratus)
–Sally Lightfoot Crab (Grapsus adscensionis)