Archive for the ‘Marine Science’ Category

Olive ridley turtle

Wednesday, November 26th, 2014

olive

Common name: Olive ridley turtle

Scientific name: Lepidochelys olivacea

Distribution: Tropical waters worldwide

Nests on: Tropical beaches worldwide

Beach type: Tropical mainland shores and barrier islands, often near river mouths.Throughout mainland; also Andaman and Nicobar and to a lesser extent, Lakshadweep Islands.

Weight (adult): Olive ridley turtle50 kg

Carapace length: 60 – 70 cm

Carapace shape: Short and wide, carapace smooth but elevated, tectiform (tent-shaped).

Colouration: Mid to dark olive green

Costal scutes: 5 – 9 pairs asymmetrical

Head shape: Large, triangular

Prefrontal scales: 2 pairs

Limbs: Two claws on each flipper

Plastron: Pore near rear margin of infra marginals; creamy yellow

Other features: Vertebrals (centrals) narrow, so that first costal contacts nuchal scute.

Time of nesting: Night

Clutches per season: 1 – 3

Clutch size: 100 – 120

Egg size: ~ 4 cm in diameter

Re-nesting interval: 20 – 28 days

Re-migration interval: 1 – 2 years

Track: 70 – 80 cm wide, light, with asymmetrical, oblique marks made by forelimbs, tail drag mark lacking or inconspicuous.

olive2

Loggerhead turtle

Wednesday, November 19th, 2014

logg

Common name: Loggerhead turtle

Scientific name: Loggerhead turtle Caretta caretta

Distribution: Tropical waters worldwide

Nests on: Temperate, sometimes subtropical and tropical waters.

Beach type: Extensive mainland beaches or barrier islands.Not known to nest in India, but does nest in Sri Lanka.

Weight (adult): 200 kg

Carapace length: 80 – 100 cm

Carapace shape: Moderately broad, lightly serrated posterior margin in immatures, thickened area of carapace at base of 5th vertebral in adults.

Colouration: Generally unmarked reddish brown in subadults and adults.

Costal scutes: 5 pairs

Head shape: Large and broadly triangular

Prefrontal scales: 2 pairs

Limbs: Two claws on each flipper

Plastron: Yellow to orange

Other features: Vertebrals (centrals) narrow, so that first costal contacts nuchal scute.

Time of nesting: Night

Clutches per season: 3 – 5

Clutch size: 100 – 120

Egg size: ~ 4 cm in diameter

Re-nesting interval: 12 – 16 days

Re-migration interval: 2 – 3 years

Track: 70 – 90 cm wide, moderately deep, with asymmetrical diagonal marks made by forelimbs, tail drag mark usually absent.

log2

Hawksbill turtle

Wednesday, November 12th, 2014

hawk

Common name: Hawksbill turtle

Scientific name: Eretmochelys imbricate

Distribution: Tropical waters worldwide

Nests on: Tropical beaches worldwide, mainly remote islands.

Beach type: Narrow beaches on islands or mainland shores, with reefs obstructing offshore approach. Lakshadweep, Andamans, and few beaches in Nicobar such as Indira Point in Great Nicobar. Hawksbills often nest under overhanging vegetation (unlike ridleys which nest in open areas).

Weight (adult): 150 kg

Carapace length: 80 – 100 cm

Carapace shape: Oval, strongly serrated posterior margin, thick imbricate scutes.

Colouration: Brown, boldly marked with amber and brown variegations.

Costal scutes: 4 pairs (ragged posterior border)

Head shape: Narrow, straight bird like beak

Prefrontal scales: 2 pairs

Limbs: Two claws on each flipper

Plastron: Light yellow to white

Other features: Vertebrals (centrals) large, so that first costal does not contact nuchal scute.

Time of nesting: Night/Day

Clutches per season: 3 – 5

Clutch size: 120 – 150 (up to 180)

Egg size: ~ 3.5 cm in diameter

Re-nesting interval: 12 – 14 days

Re-migration interval: 2 – 5 years

Track: 70 – 85 cm wide, shallow, with asymmetrical (alternating) oblique marks made by forelimbs, tail marks present or absent. Often hard to distinguish from tracks of ridleys, but the two species nest in very different beach types.

hawk2

Green Turtle

Wednesday, November 5th, 2014

green

Common name: Green turtle

Scientific name: Chelonia mydas

Distribution: Tropical and subtropical waters

Nests on: Tropical beaches worldwide, mainland and remote islands.

Beach type: Large, open beaches to small cove beaches. Mainly Gujarat on the mainland, and beaches in the Lakshadweep and Andaman Islands.

Weight (adult): 250 kg

Carapace length: 90 – 120 cm

Carapace shape: Broadly oval; margin scalloped but not serrated.

Colouration: Brown with radiating streaks in juveniles, variable in adults.

Costal scutes: 4 pairs

Head shape: Anteriorly rounded

Prefrontal scales: 1 pair

Limbs: Single claw on each flipper

Plastron: White in hatchlings, yellowish in adults

Other features: Vertebrals (centrals) large, so that first costal does not contact nuchal scute.

Time of nesting: Night

Clutches per season: 4 – 6

Clutch size: 100 – 120

Egg size: ~ 4.5 cm in diameter

Re-nesting interval: 10 – 14 days

Re-migration interval: 3 – 5 years

Track: 100 – 130 cm wide, deep, with symmetrical diagonal marks made by forelimbs, tail drag solid or broken line.

green 2

Leatherback turtle

Wednesday, October 29th, 2014

leatherback

Common name: Leatherback turtle

Scientific name: Dermochelys coriacea

Distribution: All oceans, sub-arctic to tropical waters

Nests on: Tropical beaches

Beach type: Wide beaches with steep slope, rock free deep water approach. In India, nests in the Andaman and Nicobar islands mainly. Main nesting sites are Galathea on the east coast and several beaches in the west coast of Great Nicobar, Little Nicobar and Little Andaman Islands.

Weight (adult): 500 kg +

Carapace length: 140 – 170 cm

Carapace shape: Elongate and tapering with seven prominent dorsal ridges;

scutes always absent.

Colouration: Mostly black with white spotting;

pink or bluish pots on base of neck and flippers.

Costal scutes: Absent

Head shape: Triangular; two maxillary cusps (tooth-like notch on either side of upper jaw).

Prefrontal scales: None

Limbs: Forelimbs extremely long

Plastron: Relatively small and distensible with 5 longitudinal ridges.

Time of nesting: Night

Clutches per season: 4 – 6

Clutch size: 80 – 100

Egg size: ~ 5 cm in diameter

Re-nesting interval: 9 – 10 days

Re-migration interval: 2 – 3 years

Track: 150 – 200 cm wide, deep and broad, with symmetrical diagonal marks made by forelimbs, usually with a deep median groove from the long tail.

leatherbacktrack

Visit Us On FacebookVisit Us On Youtube