Conservation and Ecology of Marine Reptiles

MARE 490Dr. Turner

Summer 2012

Mammalia

Reptilian OriginsAves Reptilia

Class Reptilia

Order Chelonia – marine turtles

Order Squamata – marine snakes and iguanas

Order Crocodilia – saltwater crocodile

Class Reptilia6,000 living species of reptiles

(lizards, snakes, turtles, crocodiles)

Dry skin covered with scales (prevent H20 loss)

Air breathing

Marine taxa include sea turtles, sea snakes, marine iguana, and saltwater crocodile

Marine TurtlesMarine turtles tied to terrestrial environment for oviposition - process of laying eggs

Other Aquatic Reptiles: iguanas, crocodilians, ichthyosaurs - tail undulation for locomotion

Marine TurtlesMarine turtles: lost capacity of tail undulation

Developed shortened, rigid body form & corselet (breastplate)

Limbs required profound modification from terrestrial existence

Limb ModificationForelimbs modified into paddles: - elongate phalanges enmeshed in a continuous matrix of tough connective tissue

Foreclaws reduced to three on each limb

Order Chelonii2 Families: Cheloniidae & Dermochelyidae

7 or 8 species found throughout 3 tropical Oceans

3 species have restricted distribution: Flatback – northern Australia Kemp’s ridley – Gulf of Mexico, N. Atlantic Black sea turtle – eastern Pacific

Order CheloniiTurtles & tortoises – monophyletic group or clade

“Pseudoturtle” Placochelys

Order CheloniiCretaceous – 4 families: Toxichelyidae Protostegidae Cheloniidae Dermochelyidae

Order Chelonii

- Extinct

- Extant

Family ToxichelyidaeSmall/medium sized, broad-shelled marine turtles - diverged from Cheloniidae

Family ProtostegidaeA group of large to gigantic turtles - Rhinochelys sp.Parallels with dermochelyidae

Family Protostegidae

Order Chelonii

- Extinct

- Extant

Family CheloniidaeShell covered in horny scutesVariable in numberTypically 5 pairs on carapace; 6 of plastron

Family DermochelyidaeReduction in bones of the carapace & plastronNo scutes

Cheloniid DiversityAt one point – 31 genera5 extant:

Chelonia sp.Eretmochelys sp.Lepidochelys sp.Caretta sp.Natator sp.

Genus CheloniaDescription: 4 pairs of lateral, non-overlapping scutes

2 extant species:Chelonia mydasChelonia agassizii

Genus CheloniaChelonia mydas: 4-pairs lateral scutes, 1 pair prefrontal scales, non-overlapping scutes, round head, serrated jaw; to 230kg, shell 125cm

Family CheloniidaeChelonia mydas – green sea turtle

Herbivore Fibrilopapilloma – 49-92%Nest French Frigate Shoals≈1,000 females

Family CheloniidaeChelonia mydas – green sea turtle

Major Nesting Areas

C. mydas

Genus CheloniaChelonia agassizii: 4-pairs lateral scutes, 1 pair prefrontal scales, non-overlapping scutes, round head, serrated jaw; to 230kg, shell 125cm

Black pigmentationRestricted to E. Pacific

Family CheloniidaeChelonia agassizii – black sea turtle

Pacific coast of S. America

4 pairs of non-overlapping lateral scutes

Family CheloniidaeChelonia agassizii – black sea turtle

Major Nesting Areas

C. agassizii

Genus EretmochelysDescription: 4 pairs of lateral, overlapping scutes

1 extant species:Eretmocheyls imbricata

Genus EretmochelysEretmocheyls imbricata: 4-pairs lateral scutes, 2 pairs prefrontal scales, overlapping scutes, pointed head, overbite; to 85kg, shell 95cm

Family CheloniidaeEretmocheyls imbricata – Hawksbill sea turtle

Shell highly prized; $100/lbUntil 1992 – 20 net tons/JapanNests on beaches of Hawaii

4 pairs of overlapping lateral scutes

Family CheloniidaeEretmocheyls imbricata – Hawksbill sea turtle

Major Nesting Areas

E. imbricata

Genus LepidochelysDescription: 5-6+ lateral scutes, round carapace

2 extant species:Lepidocheyls olivaceaLepidocheyls kempi

Olive Kemp’s

Genus LepidochelysLepidocheyls olivacea: 6+-pairs lateral scutes, carapace nearly circular, 4 bridge scutes with pores, juvenile-charcoal, adult-olive green; to 45kg, shell 70cm

Restricted to tropical waters

Family CheloniidaeLepidocheyls olivacea – Olive ridley sea turtle

Widely DistributedDoing fairly wellRarely found around Hawai′i

6+ pairs of non-overlapping lateral scutes

Family CheloniidaeLepidocheyls olivacea – Olive ridley sea turtle

Major Nesting Areas

L. olivacea

Genus LepidochelysLepidocheyls kempi: 5-6 pairs lateral scutes, carapace very round, 4 bridge scutes with pores, juvenile-charcoal, adult-grey-green; to 45kg, shell 70cm

5-6

Restricted to Gulf of Mexico & S. Atlantic

Family CheloniidaeLepidocheyls kempi – Kemp’s ridley sea turtle

Most critically Endangered1947-42,000 ♀; 1980’s -1,000♀Shrimp trawl bycatch

5 pairs of non-overlapping lateral scutes

Family CheloniidaeLepidocheyls kempi – Kemp’s ridley sea turtle

Major Nesting Areas

L. kempi

Genus CarettaDescription: 5-6 lateral scutes, carapace longer than wide

1 extant species:Caretta caretta

Loggerhead Kemp’s

Genus CarettaCaretta caretta: 5-6 pairs lateral scutes, carapace longer than wide, 3 bridge scutes with no pores, broad head, red to red-brown; to 200kg, shell 120cm

Family CheloniidaeCaretta caretta – Loggerhead sea turtle

Nests in S. Japan – only in N. Pacific; prevalent in Gulf of Mexico and Atlantic

5 pairs of non-overlapping lateral scutes

Family CheloniidaeCaretta caretta – Loggerhead sea turtle

Major Nesting Areas

C. caretta

Genus NatatorDescription: 4 pairs of lateral, non-overlapping scutes;

1 extant species:Natator depressus

Genus NatatorNatator depressus: 4-pairs lateral scutes, 1 pair prefrontal scales, non-overlapping scutes, round head, serrated jaw; to 90kg, shell 100cm

Dorso-ventrally flattened

Family CheloniidaeNatator depressus – Flatback sea turtle

Australia – limited range

4 pairs of non-overlapping lateral scutesThin, smooth, & waxy

Family CheloniidaeNatator depressus – Flatback sea turtle

Major Nesting Areas

N. depressus

Dermochelyid DiversitySingle extant species shows very little geographic variability - probably no subspecies exist

However discussion of named populations

Genus DermochelysDermochelys coriacea: Flexible, tapered, & leathery carapace, 5 distinct ridges, no scutes, jaw deeply notched; to 500kg, shell 180cm

Family DermochelyidaeDermocheyls coriacea – Leatherback sea turtle

20,000-30,000 WorldwideCaught in longlines; jellyfishSighted offshore Kona

Family DermochelyidaeDermocheyls coriacea – Leatherback sea turtle

Major Nesting Areas

D. coriacea

Current Taxonomic Questions1. What subfamilies should be recognized?2. Correct placement of flatback?3. Relationship within Lepidochelys4. Status of black turtle in eastern Pacific

Subfamilies?Probably notComplex history of OrderMore work to be done within families

Flatback TurtleWhat is the correct placement of the flatback?

Originally Chelonia depressa

Shows characteristics of both Chelonia & Lepidochelys

Systematic ControversiesNatator depressus – Taxonomic Assignment?

Originally Chelonia depressa

Actually more closely aligned with Caretta & Lepidochelys – both carnivorous

Relationship Between RidleysSlight external difference between juveniles

- only color patterns

Kemp’s Ridley Olive Ridley

Relationship Between RidleysGenetics - differences to species level

Systematic ControversiesRidleys? Believe it or not!

Readily distinguished by color but not morphometrically

Atlantic and Pacific species probably isolated due to formation of Isthmus of Panama – caused large changes in recent speciation (e.g. walrus, bottlenose dolphins, etc.

Systematic ControversiesDermocheyls coriacea – Ancient lineage?

Distinguished from other turtles by: skeletal features partial endothermy modified external morphology

Molecular evidence indicates that leatherbacks represent an early offshoot of the lineage that gave rise to extant marine turtles

Eretnochelys imbricata – Origin of unusual diet?

Appears to have arisen from a carnivorous ancestor

Genus closely aligned with Caretta & Lepidochelys – both carnivorous

“So, you think you’re sponge-worthy?” - Elaine Benice

Systematic Controversies

Systematic ControversiesMarine Turtle Hybrids – Turtle Bastards?

Loggerhead female – Green maleLoggerhead female – Hawksbill maleKemp’s Ridley female – Loggerhead maleGreen female – Hawksbill male

May be oldest vertebrate lineages known to hybridize in nature

Why Do We Care?“Well, that's why I asked. That's how you learn, by asking.. you dumbass.” - Carl Carlson

Population/species level distinction is critical for efficient management practices

International, National, State regulations

Cultural uses

Economic implications