astronomy-to-zoology:

Black-knobbed Map Turtle (Graptemys nigrinoda)

…a species of emydid turtle that is endemic to the southeastern United States, specifically the Mobile Bay drainages in Mississippi and the Tombigbee/ Black Warrior River systems in Alabama. Black-knobbed map turtles are typically active from April to late November and have a diet that consists mainly of algae, insects, mollusks, sponges and bryozoans. As its common name suggests G. nigridoda’s first four vertebrate posessing knob like processes. The second and third processes typically more dominant and will reduce with age. G. nigridoda is also sexually dimorphic with females being twice the size as males, poscessing higer carapaces, and shorter tails than males.

Currently Graptemys nigrinoda is listed as near threatened and faces threats from habitat degradation and habitat loss.

Classification

Animalia-Chordata-Reptilia-Testudines-Emydidae-Deirochelyinae-Graptemys-G. nigrinoda

Images: graptemys.com and M. North