Lecture Notes on Marine Reptiles Diversity

Overview

This lecture covers various aspects of marine reptiles including sea snakes, sea crabs, iguanas (specifically marine iguanas), saltwater crocodiles, and sea turtles. Each type of reptile has unique adaptations for survival in marine environments. Key points of discussion include the biological characteristics, habitats, and survival strategies of these reptiles.

Sea Snakes and Sea Kraits

• Family: Elapidae
• Habitat: Tropical and subtropical regions; terrestrial forms found in Asia, Australia, Africa, and the Americas; marine forms in the Pacific and Indian Oceans.
• Characteristics:
  • Venomous snakes with neurotoxins in their venom.
  • Caudal fin-like tails for swimming.
  • Require surfacing to breathe due to being air-breathing reptiles.
  • Mostly ovoviviparous (develop eggs inside their body).
  • Feed mainly on small fish.
• Example: Yellow-bellied sea snake, presence increased in California during El Nino.
• Adaptations: Able to live in water but come to land occasionally.

Marine Iguanas

• Location: Endemic to the Galapagos Islands.
• Habitat and Diet:
  • Feed on algae, diving underwater to graze.
  • Lay eggs on land.
• Behavior: Need to warm up on land after being in cold ocean water due to their ectothermic nature.

Saltwater Crocodiles (Crocodylia porosus)

• Age: Evolved around 25 million years ago.
• Size: Males can grow up to 20 feet long.
• Diet: Birds, fish, mammals, and crustaceans.
• Reproductive behavior:
  • Lay eggs.
  • Guard their nests actively.
• Distribution: Found in Australia, parts of Southeast Asia, and the eastern coast of India.

Sea Turtles

• Types:
  • Green sea turtles
  • Olive Ridley sea turtles
  • Kemp's Ridley
  • Hawksbill
  • Flatback
  • Loggerhead
  • Leatherback
• Characteristics:
  • Mostly nest on beaches and are faithful to their nesting site.
  • After hatching, young turtles rush to the sea, facing high predation rates.
• Conservation status:
  • Green sea turtle: Endangered.
  • Kemp's Ridley: Critically endangered.
  • Hawksbill: Critically endangered.
  • Leatherback: Vulnerable.
• Behavior and Adaptations:
  • Sea turtles use magnetic fields to navigate back to their nesting sites.
  • Researchers use tracking devices to study migration and habits.

In Conclusion

The diversity within marine reptiles is vast, with each group having unique adaptations that highlight the complexity of evolutionary biology and the environmental demands placed on these creatures. Understanding these marine reptiles offers insights into conservation needs and the ecological balance within their respective habitats.