The underside of these Mangrove Horseshoe Crabs shows them as in the way they swim, i.e. upside down.

These crustacean-like arthropods have stiff and pointed tails, which are rounded in the mangrove species and angular in the southern species. Holding this greenish brown Southern Horseshoe Crab by it tail, clearly shows its horseshoe-shaped carapace, that give these creatures their name.