Types of Marine Reptiles

Living marine reptiles are distributed throughout tropical and subtropical oceans and include about 70 species of sea snakes, seven sea turtle species, the saltwater crocodile and the Galapagos Marine Iguana. Each of these groups has unique characteristics and adaptations for life in the ocean, but all must return to the surface to breathe air. Most marine reptiles must spend at least part of their life cycle in terrestrial environments to reproduce.

  1. Marine Snakes

    • According to the IUCN Sea Snake Specialist Group, there are about 70 species of living sea snakes, which accounts for 86 percent of the living marine reptile species. Marine snakes occur primarily in warm tropical waters of the Indo-West Pacific; they are absent from the Atlantic Ocean and Caribbean Sea. The five evolutionary groups of marine snakes include the True Sea Snakes (marine hydrophiines; ca. 60 species), Sea Kraits (Laticauda sp.; six marine species), File Snakes (Acrochordidae; two marine species), Mangrove or Mud Snakes (Homalopsidae; three marine species), and Salt Marsh Watersnakes (Natricinae). Sea Snakes are unique among the marine snakes in that they can live their lives entirely at sea, even giving birth in the water. Sea Kraits look similar to Sea Snakes in morphology, both having flattened, paddle-like tails that seem remarkably suited to marine life, but Sea Kraits must return to land to lay eggs. File Snakes, Mangrove Snakes and Salt Marsh Watersnakes all have their own unique morphologies and adaptations to marine life, but they do not have the typical "marine" appearance of the venomous Sea Snakes and Kraits.

    Sea Turtles

    • Leatherback Sea Turtle

      The seven species of living sea turtles currently recognized by science--the Green (Chelonia mydas), Hawksbill (Eretmochelys imbricata), Kemp's Ridley (Lepidochelys kempii), Loggerhead (Caretta caretta), Olive Ridley (Lepidochelys olivacea), Flatback (Natator depressus), and Leatherback (Dermochelys coriacea) Sea Turtles--range in size from less than 100 pounds (Kemp's and Olive Ridley Sea Turtles) to between 1,300 and 2,000+ pounds (Leatherbacks). All sea turtles have streamlined bodies and large flippers, enabling them to swim gracefully, covering hundreds or even thousands of miles during migrations between nesting beaches and marine feeding areas.

    Saltwater Crocodiles

    • Saltwater Crocodiles (Crocodylus porosus) are the largest living crocodile species, reaching up to 20.7 feet long (confirmed measurement; there are unverified reports of larger individuals) and 2,200 pounds. Found in Southeast Asia, Northern Australia, along the Eastern coast of India and in surrounding waters, Saltwater crocodiles live in a variety of aquatic habitats, including saltwater and brackish water habitats, freshwater wetlands and rivers.

    Galapagos Marine Iguanas

    • Marine Iguanas

      Galapagos Marine Iguanas (Amblyrhynchus cristatus) are the only living lizard species known to forage almost entirely in the sea. Endemic to the Galapagos Islands, Marine Iguanas have spread throughout the entire archipelago, where they spend the majority of their time basking on the rocky coastline and foraging in the sea and tidal areas for seaweed and algae. Marine Iguanas are capable of staying submerged up to 30 minutes at depths of 50 feet, but such prolonged dives makes them vulnerable to predators such as sharks and large fish. Consequently, they also tend to feed on exposed rocks in tidal areas, which are warmer than the deeper seawater.