Conservation and Ecology of Marine Reptiles MARE 494 Dr. Turner Summer 2006

1. Conservation and Ecology of Marine Reptiles MARE 494 Dr. Turner Summer 2006

2. Thermo & Osmo Regulation Live in unique marine media that causes problems with thermal biology and regulation of salt & water Like other marine animals have adaptations which allow for survival

3. Thermal Biology Ultimately tied to thermal constraints of their environment Sea turtles are unusual among reptiles – large body size allow adults to use insulation & blood flow to alter (control) body temperature (Tb) Large difference in thermal patterns among hatchlings, juveniles, & adults

4. ??? Thermal Biology Conformer:Physiological state = environment Regulator: Physiological state different from environment Conformer Body Temp Regulator 0 10 20 30 Ambient Temp

5. Heat Exchange

6. Lets Get Biophysical Energy exchange controls the TB of sea turtle Chemical energy drives metabolism & provides and internal heat source Energy from the environment is main source of heat for sea turtles (land or sea) except for very large animals

7. Surf & Turf In water thermal radiation absorbed near surface – heat exchange is by: Conduction Convection On land heat energy exchange is by: Radiation Convection Evaporation Conduction

8. Energy Balance Equations Qabs + M = R + C + E + G Qabs = radiation absorbed by the surface of the animal from the sun M = metabolic heat production R = thermal heat emitted by surface of the animal C = heat energy lost by convection E = heat energy lost by evaporation/gained by condensation G = heat energy lost or gained by conduction through direct contact with soil, water, or substrate HEAT IN = HEAT OUT + HEAT STORED

9. Land! Sea turtles nest at night because exposure to the hot sun during the day would lead to lethal heat gain Gradient across thickness of carapace & plastron causes internal heat lag between surface & deep body However, deep body it not great enough heat sink to sustain but a few degrees ambient temperature increases

10. Basking! Sea turtles bask on land & in water Turtles that bask on land typically seek out beaches facing outer reefs and prevailing trade winds Lower temps than on beaches on opposite side of Island Do we see this in practice? Punalu‘u versus Kona

11. Regulate to Regulate How do basking turtles regulate internal temperatures? Flip sand onto flippers & carapace reduce surface temperature > 10°C Flipper into water reduce surface temperature > 10°C+

12. Cold-Stunned Occurs when temperatures drop below 8°C Lose ability to swim & dive, buoyancy control, float to surface, & die Probably disruption of metabolic pathways

13. Thermoregulation? Are leatherback sea turtles homeothermic? Metabolic rate higher than cheloniids; higher than typical reptile scaled to its size Still ½ the metabolic rate of mammals May allow enough for these large turtles to function at very cold temperatures during deep diving bouts – oceanic existence

14. Tag’em & Bag’em “Since they stopped testing on animals, a guy like me can really clean up!” – Barney Gumble

15. Osmoregulation? Are leatherback sea turtles homeothermic? Metabolic rate higher than cheloniids; higher than typical reptile scaled to its size Still ½ the metabolic rate of mammals May allow enough for these large turtles to function at very cold temperatures during deep diving bouts – oceanic existence

16. Coping with Salinity “Yaarh! I hate the sea and everything in it” - Captain Horatio McCallister Some molluscs

17. Osmo Kramer “These pretzels are making me thirsty!” – Kosmo Kramer Sea turtles live in medium that is almost 3X more concentrated than body fluids Some ions greater – 23X Mg2+ Must maintain internal osmotic & ionic homeostatis

18. Salt! Salt Concentration

19. Reptile Profile Respiration not a major source of water loss in marine reptiles Water loss function of permeability of transcutaneous osmotic gradient Water loss via urine & feces (cloaca) low

20. Na+Na+Na+Na+, HeyHeyHey, Goodbye Na+ efflux at similar levels to marine elsambranchs (lower than teleosts) Sea turtles have low epithelia permeability for Na+ Bulk of salt loss is from salt gland 60% in loggerhead 90% in green

21. Salt Ingestion Ingestion major source in salt intake Esophagus provides protection against incidental drinking – papillae & sphincter help to “trap” food; expel water

22. Glands! Reptiles have a unique variety of organs used as salt glands Salivary glands – sea snakes Lingual glands – crocodiles Nasal glands – lizards Lachrymal gland – sea turtles 2X size of leatherback brain

23. Salt Gland Powers, Activate “Brian, take out your ring. Wonder Twin powers activate. Shape of steam.” "Peter, we got these from a box of fruit loops” – Peter & Brian Griffin When actived - discharges a fluid 6X that of blood; 2X seawater When inactive – ¼ the concentrating capability Greater than marine birds; 2X shark rectal gland Unlike avian glands – remove Mg2+

24. Salt Gland vs. Kidney