Fiddler crab Fiddler crab A fiddler crab, sometimes known as a "calling crab", may be any of approximately 100 species of semi-terrestrial marine crabs which make up the genus Uca. As members of the family Ocypodidae, fiddler crabs are most closely related to the ghost crabs of the genus "Ocypode". This entire group is composed of small crabs – the largest being slightly over two inches across. Fiddler crabs are found along sea beaches and brackish inter-tidal mud flats, lagoons and swamps. Fiddler crabs are most well known for their sexually dimorphic claws; the males’ major claw is much larger than the
Wall spider Wall spider Wall spider is the common name for members of the genus Oecobius. The members of these several species are all very small spiders that make small flat webs over crevices in walls and in similar spaces. They possess an organ called a cribellum, which is a kind of comb-like device used to separate fibers of silk drawn from its spinnerets into many extremely fine fibers. Those fibers are so small in diameter that prey insects easily become entangled in them. The spiders then bite them before they can get away. One cosmopolitan species is "O. navus" (sometimes also