Lucas Bustamante / Red tailed boa constrictor (Boa constrictor constrictor) juvenile, portrait, with tail wrapped round head, Cuayabeno, Sucumbios, Ecuador.

John Cancalosi / Boa Constrictor (Boa constrictor) shedding skin from head. Guanacaste National Park, Costa Rican tropical rainforest.

John Cancalosi / Boa Constrictor (Boa constrictor) shedding skin from head. Guanacaste National Park, Costa Rican tropical rainforest.

Michael D. Kern / Red Tailed Boa {Boa constrictor constrictor} captive, from South America

Mary McDonald / Boa constrictor (Constrictor constrictor). South America

Pete Oxford / Boa Constrictor (Boa constrictor) coiled around a mossy tree branch in the rainforest, South America

George Sanker / Everglades racer (Coluber constrictor paludicola) with tongue out. Everglades National Park, Florida, USA. March.

George Sanker / Everglades racer (Coluber constrictor paludicola). Everglades National Park, Florida, USA. March.

George Sanker / Everglades racer snake (Coluber constrictor paludicola). Everglades National Park, Florida, USA. March.

Karine Aigner / Eastern yellow-bellied racer (Coluber constrictor flaviventris), eating a checkered garter snake (Thamnophis marcianus). Texas, USA, July.

Jen Guyton / Pale morph Boa constrictor (Boa constrictor) from Tayrona National Park, Colombia. Controlled conditions.

Jen Guyton / Boa constrictor (Boa constrictor) Tayrona National Park, Colombia.