9.1 Marine reptiles: sea turtles and sea snakes

Marine reptiles have evolved remarkable adaptations for life in the ocean. Sea turtles boast streamlined shells and powerful flippers, while sea snakes have paddle-like tails and salt glands. These features allow them to thrive in aquatic environments.

Despite their adaptations, marine reptiles face numerous threats. Sea turtles are endangered due to habitat loss and bycatch, while sea snakes are often overlooked in conservation efforts. Both groups play crucial ecological roles, from maintaining seagrass beds to regulating fish populations.

Marine Reptile Adaptations and Ecology

Adaptations of marine reptiles

Top images from around the web for Adaptations of marine reptiles

• 

  Sea turtle - Wikipedia View original

  Is this image relevant?

• 

  Animals characteristics | Unidad 4: Vida oceánica. View original

  Is this image relevant?

• 

  Types of Ocean Organisms | Physical Geography View original

  Is this image relevant?

• 

  Sea turtle - Wikipedia View original

  Is this image relevant?

• 

  Animals characteristics | Unidad 4: Vida oceánica. View original

  Is this image relevant?

1 of 3

Top images from around the web for Adaptations of marine reptiles

• 

  Sea turtle - Wikipedia View original

  Is this image relevant?

• 

  Animals characteristics | Unidad 4: Vida oceánica. View original

  Is this image relevant?

• 

  Types of Ocean Organisms | Physical Geography View original

  Is this image relevant?

• 

  Sea turtle - Wikipedia View original

  Is this image relevant?

• 

  Animals characteristics | Unidad 4: Vida oceánica. View original

  Is this image relevant?

1 of 3

• Sea turtles have evolved several adaptations for efficient swimming and diving in marine environments:
  • Streamlined shell reduces drag and improves hydrodynamics
  • Flippers provide powerful propulsion and precise steering control
  • Salt glands excrete excess salt ingested from seawater to maintain osmotic balance
  • Ability to hold breath for extended periods during prolonged dives (up to several hours in some species)
  • Leathery shell in some species (leatherback turtles) enhances flexibility and reduces weight for deep diving
• Sea snakes possess unique adaptations that enable them to thrive in marine habitats:
  • Laterally compressed tail acts as a paddle for efficient swimming
  • Valved nostrils prevent water entry when submerged
  • Salt glands maintain osmotic balance by excreting excess salt
  • Neurotoxic venom aids in prey capture and defense against predators
  • Cutaneous respiration allows oxygen uptake through the skin, supplementing lung breathing

Sea turtles vs sea snakes

• Sea turtles have complex life cycles that involve both terrestrial and marine phases:
  • Females lay eggs on sandy beaches, which incubate and hatch after several months
  • Hatchlings emerge and navigate to the ocean using visual and magnetic cues
  • Juveniles spend years in open ocean habitats (often associated with floating sargassum)
  • Adults return to their natal beaches for nesting, showing strong site fidelity
  • Omnivorous diet that varies by species (jellyfish, seagrass, crustaceans, sponges)
• Sea snakes, in contrast, spend their entire life cycle in marine environments:
  • Viviparous reproduction, giving birth to live young in the ocean
  • Young are independent from birth and must fend for themselves
  • Specialized predators that feed primarily on fish and eels
  • Some species undertake seasonal migrations between feeding and breeding grounds
• Despite differences, sea turtles and sea snakes share some common characteristics:
  • Ectothermic, relying on external heat sources to regulate body temperature
  • Need to surface regularly to breathe air, although dive durations vary
  • Face similar anthropogenic threats such as habitat loss, bycatch, and pollution

Conservation and Ecological Importance

Conservation of marine reptiles

• Sea turtles are among the most threatened marine vertebrates, with all species classified as threatened or endangered:
  • Habitat loss and degradation, particularly of nesting beaches and foraging areas (coral reefs, seagrass beds)
  • Incidental capture (bycatch) in fishing gear such as longlines, trawls, and gillnets
  • Poaching of eggs and adults for consumption and trade of shell products
  • Climate change impacts on nesting success and sex ratios (temperature-dependent sex determination)
  • Conservation measures include protected areas, beach monitoring, fishing gear modifications (turtle excluder devices), and international trade regulations (CITES)
• Sea snakes face similar threats but are often overlooked in conservation efforts:
  • Habitat destruction and pollution of coastal areas and coral reefs
  • Bycatch in trawl fisheries, particularly in the Indo-Pacific region
  • Overexploitation for their skin (leather industry) and meat (local consumption)
  • Many species lack sufficient data for proper conservation assessment and management
  • Limited conservation measures in place, with a need for improved monitoring and protection

Ecological roles in marine ecosystems

• Sea turtles play important ecological roles in the marine ecosystems they inhabit:
  • Herbivorous species (green sea turtles) maintain the health and productivity of seagrass beds through grazing
  • Carnivorous species (loggerhead turtles) help control populations of invertebrates such as crabs, mollusks, and jellyfish
  • Nesting activities transfer nutrients from marine to terrestrial ecosystems, supporting coastal vegetation and fauna
  • Serve as prey for large predators such as sharks, contributing to energy transfer in food webs
• Sea snakes also have significant ecological functions in marine habitats:
  • Act as predators of fish and eels, helping to regulate their populations and maintain ecosystem balance
  • Venomous species may influence the behavior and distribution of their prey species
  • Some species are preyed upon by larger marine predators (sharks, birds, fish), facilitating energy flow
  • Potential indicators of ecosystem health and pollution levels due to their sensitivity to environmental changes