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Where do they?
海龜是海洋龜類的總稱，是所有龜鱉類動物中唯一生活在海洋的物種。
屬動物界中有脊椎的爬行類動物。

現存海龜種類共有有2科6屬7種，這兩科分別為蠵龜科和革龜科。
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，約有95％的忠誠度會回到當初出生地，進行交配產卵。

在東亞海域可發現的海龜有5屬5種，除平背龜主要分佈於澳洲北部海域，肯氏龜主要分佈於加勒比海外。

What do they look like?
海龜背上有殼，較一般陸龜或河龜來得花紋複雜，殼的外型是扁平流線形。海龜的腳為適應長途游泳，演化成船槳狀。

What do thay eat?
海龜只是一個總稱，不同海龜的主食都不大相同。
例子：
革龜，主食為水母。
赤蠵龜，主食為甲殼類軟體動物
欖蠵龜，以甲殼類為主食。
玳瑁，以珊瑚礁處的海綿等軟體動物為主食。
綠蠵龜，以大型海草及海藻為主食。

What is special about them?
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，古海龜的英文稱為en:Archelon，據北美的考古化石發現，古海龜的體型相當驚人，長達3.5公尺，與汽車一般大小。外殼有明顯的節骨狀。
圖片：http://upload.wikimedia.org/wikipedia/commons/a/a1/Chelonia_mydas_%28Hawaiian_variety%29.jpg

Where do they?
Sea turtles are found in warm and temperate seas throughout the world.

What do they look like?
Sea Turtles are large, air-breathing reptiles that inhabit tropical and sub-tropical seas throughout the world. There are different species but they all share some common characteristics. The most obvious and well known is their shell. This consists of two pieces, the upper part called the carapace and the lower section called the plastron. This shell protects them from being eaten and bashed around by the ocean. Hard scales, or scutes, cover all but the leather-back turtle, and the number and arrangement of these can help determine the species. They do not have teeth, but their jaws have modified "beaks" suited to their particular diet. They do not have ears but ear drums covered by skin. They have excellent sense of smell and their vision underwater is good, but they are nearsighted out of water. All turtles have four modified legs that have been flattened into flippers. These help propel them through the water.

What do they eat?
-Food preferences and resources.
Diet varies with species. Sea turtles may be carnivorous (meat eating), herbivorous (plant eating), or omnivorous (eating both meat and plants). The jaw structure of many species indicates their diet.
1. Green and black sea turtles have finely serrated jaws adapted for a vegetarian diet of sea grasses and algae. In adulthood, they are the only herbivorous sea turtles, but in an aquarium environment all sea turtle species can be maintained on a carnivorous diet.
2. Loggerheads' and ridleys' jaws are adapted for crushing and grinding. Their diet consists primarily of crabs, mollusks, shrimps, jellyfish, and vegetation.
3. A hawksbill has a narrow head with jaws meeting at an acute angle, adapted for getting food from crevices in coral reefs. They eat sponges, tunicates, shrimps, and squids.
4. Leatherbacks have delicate scissor like jaws that would be damaged by anything other than their normal diet of jellyfish, tunicates, and other soft-bodied animals. The mouth cavity and throat are lined with papillae (spinelike projections) pointed backward to help them swallow soft foods.
5. Researchers continue to study the feeding habits of flatbacks. There is evidence that they are opportunistic feeders that eat seaweeds, cuttlefish, and sea cucumbers.
-Eating habits.
Some species change eating habits as they age. For instance, green sea turtles are mainly carnivorous from hatchling until juvenile size; they then progressively shift to an herbivorous diet.

What is special about tham?
Social behavior.
1. Sea turtles are not generally considered social animals; however, some species do congregate offshore.
2. Sea turtles do gather together to mate. Members of some species travel together to nesting grounds.
3. After hatchlings reach the water they generally remain solitary until they mate.
Individual behavior.
Little is known about the individual behavior of sea turtle species.
1. Green sea turtles are considered solitary, but occasionally from feeding aggregations in shallow waters abundant in seagrass or algae.
2. In the ocean, flatback turtles may spend hours at the surface floating, apparently asleep or basking in the sun. Frequently, seabirds perch on the backs of the flatbacks.
3. Hawksbill turtles spend some time resting or sleeping wedged into coral or rock ledges.
4. Olive ridleys have been observed basking on beaches, and it is not unusual to see thousands of olive ridleys floating in front of their nesting beaches.

2006-10-19 17:23:30 補充：
5. Leatherback turtles tend to dive in a cycle that follows the daily rising and sinking of the dense layer of plankton and jellyfish. The turtles probably feed in the upper layers of water at night.

海龜是海洋龜類的總稱，是所有龜鱉類動物中唯一生活在海洋的物種。背上有殼，較一般陸龜或河龜來得花紋複雜，殼的外型是扁平流線形。海龜的腳為適應長途游泳，演化成船槳狀。

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，古海龜的英文稱為en:Archelon，據北美的考古化石發現，古海龜的體型相當驚人，長達3.5公尺，與汽車一般大小。外殼有明顯的節骨狀，可參考圖片。

全球現存海龜種類共有有2科6屬7種，這兩科分別為蠵龜科和革龜科。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，約有95％的忠誠度會回到當初出生地，進行交配產卵。

在東亞海域可發現的海龜有5屬5種，除平背龜主要分佈於澳洲北部海域，肯氏龜主要分佈於加勒比海外。

[編輯]
各種海龜列表
革龜 （Leatherback turtle）學名：Dermochelys coriacea
前鰭肢長1公尺以上且無爪，體色為黑或深藍色，具有白色小點，背甲後端較尖，成龜重約500公斤，背甲長180公分。
主食為水母。
赤蠵龜（Loggerhead turtle）學名：Caretta caretta
背甲呈橢圓形，頭約20公分寬，通常為棕色或紅棕色，可重達200公斤，背甲長120公分。
主食為甲殼類軟體動物
肯氏龜（Kemp's Ridley turtle）學名：Lepidochelys kempii
背甲接近圓形，為橄欖綠色，體型小，成龜重約45公斤，背甲長70公分。
欖蠵龜（Olive Ridley turtle）學名：Lepidochelys olivacea
背甲略微橢圓，體色為深灰綠色，成龜重約45公斤，背甲長70公分。
食性與赤蠵龜相似，以甲殼類為主食。
玳瑁（Hawksbill turtle）學名：Eretmochelys imbricata
背甲的盾片呈覆瓦狀排列，有個像似鷹嘴的口喙，成龜為棕色、橘色或黃色，可重達85公斤，背甲長95公分。
以珊瑚礁處的海綿等軟體動物為主食。
綠蠵龜（Green turtle）學名：Chelonia mydas
背甲呈橢圓形，鋸齒狀的下頷，成龜從淺棕色有大花斑至近黑色，可重達230公斤，背甲長125公分。
以大型海草及海藻為主食。
平背龜（Flatback turtle）學名：Natator depressus
背甲近圓形且扁平，緣盾具有一層薄的蠟質，背甲為欖灰色，邊緣為棕黃色，成龜重約90公斤，背甲長1公尺以上。

http://www.cccturtle.org/
http://ited.yingwa.edu.hk/~ywc00433/My%20web%2049.htm
http://www.seaturtle.org/
http://www.seaturtlehospital.org/
http://www.cccturtle.org/sea-turtle-information.php?page=green
http://www.nmfs.noaa.gov/pr/species/turtles/green.htm
http://www.nmfs.noaa.gov/pr/species/turtles/
http://www.myfwc.com/seaturtle/
http://www.turtles.org/
http://www.gmtcs.org.gy/
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