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Marine Turtles (Honu) PowerPoint PPT Presentation


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Marine Turtles (Honu). History. Found in fossil record 200 mya (Triassic) Common in Cretaceous ( 130 mya ) Present day genera originated 60 (Eocene) and 10 mya (Pleistocene) Not a very diverse group Mostly tropical and subtropical. Taxonomy. Class Reptilia.

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Marine Turtles (Honu)

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Marine Turtles (Honu)


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History

Found in fossil record200 mya(Triassic)

Common in Cretaceous(130 mya)

Present day genera originated60(Eocene)and10 mya(Pleistocene)

Not a very diverse group

Mostly tropical and subtropical


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Taxonomy

Class Reptilia

Order Chelonia- warm to temperate and boreal seas ex. leatherback, ridley's, kemps

Order Chelonia-

F. Cheloniidae-green, flatback, hawksbill,

loggerhead

F. Dermochelidae- leatherback

reduced shell, dermal bone scutes compose

shell

F. Emydidae- diamond back terrapin

Hawaii species- green, hawksbill, leatherback, Olive Ridley


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Conservation Status

  • International Union for the Conservation of Nature (IUCN), also called the World Conservation Union

  • The Convention on International Trade in Endangered Species (CITES)

  • The United States Fish and Wildlife Service.

  • Endangered-facing a very high risk of extinction in the wild

  • Vulnerable -facing a high risk of extinction in the wild

  • Threatened-close to qualifying in one of the above categories


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flatback

Class:Reptilia: Reptiles

Order:Chelonia: Turtles and Tortoises

Family:Chelonidae: Marine Turtles

Scientific Name:Natator depressus

Diet:sea cucumbers, soft corals, jellyfish

Size:< 1 m in length

Conservation Status:vunerable

Habitat:near continental shelf, shallow, soft bottom sea beds

Range:northern part of Australia


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Green turtle

Class: Reptilia: Reptiles

Order: Chelonia: Turtles and Tortoises

Family: Chelonidae: Marine Turtles

Scientific Name: Chelonia mydas

Diet: seagrass and algae

Size: ~500lbs

Conservation Status: threatened

Habitat: high energy ocean beaches, convergence zones in the pelagic habitat, benthic feeding grounds in relatively protected waters

Range:throughout world in all tropical and subtropical oceans


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hawksbill

Class: Reptilia: Reptiles

Order: Chelonia: Turtles and Tortoises

Family: Chelonidae: Marine Turtles

Scientific Name:Eretmochelys imbricata

Diet: Shellfish

Size:76 - 91 cm (30 - 36 in)

Conservation Status: Endangered

Habitat: coral reefs, rocky coasts

Range: Tropical Atlantic, Pacific and Indian Oceans; Caribbean


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Loggerhead

Class: Reptilia: Reptiles

Order: Chelonia: Turtles and Tortoises

Family: Chelonidae: Marine Turtles

Scientific Name:Caretta caretta

Diet: Crustaceans

Size:76 - 102 cm (30 - 40 in)

Conservation Status:Vulnerable

Habitat: coasts, open sea

Range: Temperate and tropical areas of the Pacific, Indian and Atlantic Oceans


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leatherback

Class: Reptilia: Reptiles

Order: Chelonia: Turtles and Tortoises

Family: Dermochelidae: Marine Turtles

Scientific Name: Dermochelys coriacea

Diet: sea jellies and salps

Size: 1500 lbs

Conservation Status: endangered

Habitat: pelagic water

Range: tropical seas, oceanic islands, Atlantic, Pacific, & Indian Ocean


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  • reduced shell,

  • dermal bone scutes

  • compose shell

  • 7 dorsal and 5

  • ventral dermal bones


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Adaptation to the Marine Environment

Physiology:

Poikilothermic (cold blooded)

Skin has scales

Speed- 35 mph

Breath holding- 2 hrs, when sleeping or resting

Maturity- 10-50 yrs for green

Cannot retract heads like terrestrial turtles

Lacrimal gland- salt secretion (drinks seawater)


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Anatomy

Has both internal and external skeleton- provided protection and support for organs

Fused ribs

Powerful sense of smell- find natal beach

No ears, but can perceive low frequency sound and vibrations

Male & female- difference in tail size; males tail extends past rear flippers, females is shorter


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Reproduction

Mating- at sea

Migration- occurs in late spring; female is accompanied by male

Green sea turtles migrate as far as 800 miles from feeding area to nest in Northwestern Hawaiian Islands

Egg laying behavior- return to same beach (natal beach)


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Kemps Ridley nesting

Usually nest at night

Front flippers dig pit, rear flippers carve out burrow


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Egg tooth- used to chip away at shell

Group effort to get out of nest- emerge at night (safer) and head towards brightest light

Artificial lights- confuse hatchlings

Turtle nest

Cross section


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Leatherback hatching

Kemps Ridley hatchlings

Clutch size- about 100 eggs & covers pit with sand

Egg incubation- 2 months depending upon species

Sex determined by temperature- males lower temp, females higher temp


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Prey


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Prey

Sea grass and Algae- adult green sea turtle

Epiphyteson sea grass,

Sponges, fish, crabs, conch-loggerheads (suction feeders)

Gelatinous zooplankton:

siphonophores

jellyfish

Crustaceans, mollusks, echinoderms-Ridley


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Predators

Eggs- skunks, raccoons, pigs, lizards, crabs, ants, beetles, fungal and bacterial infections

Hatchlings- birds, mammals, crabs

Adults- sharks, humans


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Factors Affecting Green Sea Turtle Population

Hawaii-100-350 nesting females

French Frigate Shoals in the Northwest Hawaiian chain

  • Hunters

  • Fisheries

  • Marine Debris

  • Coastal Development and Habitat Degradation

  • Fibropapilloma


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Commercial Value

  • Meat

  • Eggs- nearly forbidden in all countries

  • with nesting beaches

    • Soup

    • Jewelry

    • Leather

  • Convention on International Trade in Endangered Species (CITES): turtle commerce prohibited in countries that signed agreement


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    Protection and Management

    Law enforcement- in Hawaii, turtles protected under Endangered Species Act

    Riding or harassing- $100,000 fine + prison time

    Bringing turtle products into Hawaii- $20,000 + prison time

    Fishing regulations-

    Shrimp Trawlers - incidental catch by commercial shrimp fish nets: drowned 10,000 turtles each year

    Drift nets, gill nets

    Turtle Excluder Device (TED)

    Increase sea turtle populations:

    Ranching- eggs or hatchlings from wild populations

    Farming- originally from wild populations,

    for breeding stock


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    Catch Statistics (1987) FAO yearbook on Fishery Statistics

    3100 metric tons

    Western Central Atlantic-1200

    Eastern Central Pacific- 864

    South East Pacific- 305

    Western Central Pacific- 258

    North West Pacific- 190

    Eastern Central Atlantic- 153

    Eastern Indian Ocean- 50

    Western Indian Ocean- 37

    Mediterranean - 20

    South East Atlantic- 10


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    Marine Debris- plastic bags, soda can plastic rings, fishing line, oil and tar

    Costal development and habitat degradation- noise, light, beach obstructions- affect nesting habitat


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    Fibropapilloma- virus in Green turtles

    Affects ability to feed, see, move about, or breath

    May be due to pollutants, blood parasites, or habitat change

    Kaneohe Bay (1991)- >50% infected


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    Turtle

    Excluder

    Device


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