Do sea turtles like to gather or keep social distance?
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海龜 Sea turtles

 

海龜是海洋龜類的總稱,所有龜鱉目動物中唯一生活在海洋的物種,分布範圍十分廣泛,分布於除北冰洋外的全球海域中。背上有殼,其花紋較一般陸龜或河龜複雜,殼的外型是扁平流線形,腳為船槳狀。

 

海龜的演化歷史相當悠久,可追尋到七千五百萬年前的白堊紀時期,當時海龜是肉食性的,這類海龜稱為古海龜,據北美的考古化石發現,古海龜的體型長達3.5公尺,與汽車一般大小,且外殼有明顯的節骨狀。

 

全球現存海龜種類共有有2科6屬7種,這兩科分別為海龜科和棱皮龜科。海龜喜歡熱帶及溫帶淺海水域,以肺呼吸,產卵時必須回到陸地上,不同海龜的主食都不大相同,多數海龜都是迴游性的,在繁殖季時會從覓食棲地回到產卵棲地,多數會回到當初出生地,進行交配及產卵。

 

Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the green sea turtle, loggerhead sea turtle, Kemp's ridley sea turtle, olive ridley sea turtle, hawksbill sea turtle, flatback sea turtle, and leatherback sea turtle.

 

For each of the seven types of sea turtles, females and males are the same size; there is no sexual dimorphism. In general, sea turtles have a more fusiform body plan than their terrestrial or freshwater counterparts. This tapering at both ends reduces volume and means that sea turtles can't, as can other turtles and tortoises, retract their head and limbs into their shells for protection. But the streamlined body plan reduces friction and drag in the water and allows sea turtles to swim more easily and swiftly.

 

The leatherback sea turtle is the largest sea turtle, measuring 2–3 m (6–9 ft) in length, 1–1.5 m (3–5 ft) in width, and weighing up to 700 kg (1500 lb). Other sea turtle species are smaller, being mostly 60–120 cm (2–4 ft) long and proportionally narrower.

 

The skulls of sea turtles have cheek regions that are enclosed in bone. Although this condition superficially resembles that found in the earliest known fossil reptiles it is very likely a more recently evolved trait in sea turtles.

 

海龜喜歡群聚還是保持社交距離?

您看過海底總動員嗎?電影中尼莫、多莉和綠海龜家族一起乘著東澳洋流到達雪梨的畫面,其實在現實生活中是不太會發生的喔!

海龜們除了交配和孵卵期間以外,大多數時間是不太會跟其它海龜有關聯的。所以很多時候海龜都是孤獨一隻龜在大海裡翱翔。

 

Do sea turtles like to gather or keep social distance?

Sea turtles are generally solitary creatures that remain submerged for much of the time they are at sea, which makes them extremely difficult to study. They rarely interact with one another outside of courtship and mating. Ridleys, however, do come together in massive groups during nesting.

2020-09-16
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