NON RESIDENT NATIVES: turtles, sea snake and sea krait

Herpetofaunal category
Species in complex without synopsis

Chelonia mydas

Common names: Green turtle

Eretmochelys imbricata

Common names: Hawksbill turtle

Dermochelys coriacea

Common names: Leatherback turtle

Caretta caretta

Common names: Leatherback turtle

Lepidochelys olivacea

Common names: Olive Ridley turtle

Pelamis platarus

Common names: Yellow-bellied sea snake

A variety of marine reptiles visit our waters, with most being found in northern New Zealand. Sea turtles and sea snakes are usually accidentally caught in nets, or found on shore (in most cases sick, injured, or exhausted). There are no reptile species known to breed in New Zealand.

Turtles

Green turtle (Chelonia mydas) - endangered

Green turtle are non breeding residents of New Zealand’s Kermadec Islands. The species are occasionally spotted in Northern New Zealand, and were recorded once at Banks Peninsular in the South Island in 1987. The name is derived from the green colour of their fat stores rather than as a description of the carapace (shell) or skin colour.  The carapace is olive to brown with fine dark mottling, ventral (lower) surfaces are yellow to white. Green turtles have a tear drop shaped carapace which reach sizes of up to 110cm, with individuals weighing up to 182kg. There are four costal scales, carapace (shell) shields do not overlap. A herbivorous species which inhabit lagoons feeding on seaweed and sea grass.

Hawksbill turtle (Eretmochelys imbricata) – critically endangered

Hawksbill turtle inhabit tropical waters preferring lagoons, bays, coral, or rocky reefs. They are occasional visitors in northern New Zealand. Their name reflects their characteristic sharp curving beak. The carapace is heart shaped, elongating with age reaching lengths of up to 90cm.  Carapace are striking with a variegated or marbled pattern of brown, black, or cream. The edges of the carapace are serrated and the shields overlap (except in elderly individuals where the carapace is no longer serrated and shields sit side by side). The ventral (lower) surface is yellow. Individuals can weigh up to 68kg. Hawksbill turtle are omnivorous, feeding on sponges, molluscs, crustaceans, algae and fish. The species are biofluorescent, likely due to their consumption of biofluorescent organisms such as the coral Physogyra lichtensteini.

Leatherback turtle (Dermochelys coriacea) - vulnerable

A regular visitor to New Zealand waters, venturing as far as Stewart Island. Leatherback turtle are found in tropical and temperate seas, only coming ashore to lay eggs. The carapace is dark brown or black (sometimes with a bluish tinge), with white or pink spots. The ventral (lower) surface is off white. The carapace has several longitudinal ridges and has a thick leathery skin (from which the species name derives). Leatherback turtle are the largest of all living turtles, reaching carapace lengths of up to 280cm and individuals weigh up to 700kg. An omnivorous species with jellyfish making up the core part of their diet, they also feed on cephalopods and tunicates.

Loggerhead turtle (Caretta caretta) - vulnerable

Loggerhead turtle inhabit tropical and temperate waters and are occasional visitors to New Zealand. The name derives from the latin ‘caretta’ which translates to ‘tortoiseshell’. The carapace is brown to reddish brown with a mottled cream and black pattern. The ventral (lower) surface is cream/yellow. Loggerhead turtle reach carapace lengths of up to 110cm, with adults weighing around 135kg. An omnivorous species with a wide and varied diet including, but not limited to: invertebrates, corals, sponges, sea anemones, barnacles and starfish. Loggerhead turtle are the most commonly kept species in captivity worldwide.

Olive ridley turtle (Lepidochelys olivacea) – vulnerable

Olive ridley turtle prefer warm tropical waters and are a very rare visitor to New Zealand waters. The carapace is a dull olive grey, with ventral (lower) surfaces) being whitish in colour. Carapace scutes do not overlap and have six or more costal shields on each side. The species reach carapace lengths of up to 70cm, and weight between 25 and 46kg. A predominantly carnivorous species which feed on a variety of invertebrates, jellyfish and fish eggs,

Snakes

New Zealand has a reputation for being snake free, however, two species of sea snake have been recorded visiting our shores. Unlike sea snakes, sea kraits spend part of their time on land, resting, laying eggs, or seeking fresh drinking water.

Banded sea krait and yellow-bellied sea snake are venomous and should not be approached. If you think you have spotted one keep your distance, and call 0800 HOTDOC (0800 362 468).

Banded sea krait (Laticauda colubrina)

Also known as the yellow lipped sea krait, or colubrine sea krait. The dorsal (upper) surfaces are mid grey while the ventral (lower) surface is whitish grey with black bands encircling the body. Banded sea snake reach lengths of up to 140cm. The species inhabit coastlines, often coming ashore to rest and find fresh drinking water. Banded sea snake have occasionally been found on North Island beaches (Castlepoint, Ohope Beach, Whangaruru Harbour).

Yellow-bellied sea snake (Pelamis platarus)

A slender snake which reaches lengths of up to 100cm. Dorsal (upper) surface dark brown/black, ventral (lower) surface yellow. The yellow and black meet sharply on each flank forming a straight line along the body. The tail, which is compressed sideways to form a paddle, is yellow with black spots or bars. Yellow bellied sea snake feed on fish such as mullet, anchovies, and juvenile dolphin fish. Around 6-10 yellow bellied sea snakes are sighted each year, usually around the north east coast of the North Island.

References

  • Australian Government Department of Environment and Energy (2016). Species Profile and Threats Database, “Pelamis platurus – yellow-bellied seasnake”. Retrieved October 4, 2016 from: http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=1091
  • Gill, B.J., & Whitaker, A.H. (2007). New Zealand frogs and reptiles. Auckland: David Bateman Limited.
  • Hitchmough, R.A., Barr, B., Lettink, M., Monks, J., Reardon, J., Tocher, M., van Winkel, D., Rolfe, J. (2016). Conservation status of New Zealand reptiles, 2015; New Zealand threat classification series 17. Wellington: New Zealand Department of Conservation.
  • Jewell, T. (2011). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland Publishers Ltd.