海星的英文简介（急!求）

海星的英文简介（急!求）
海星的英文简介（急!求）

海星的英文简介（急!求）
Anatomy:
Sea stars are radially symmetrical, and their arms are arranged around a central disk. Most species have five arms, however sun stars can have as many as 40 arms or more! Most sea stars are small usually measuring 12-24 cm across, but there are some species that can be very small or very large. For example, Pycnopodia, the many-rayed star of the Pacific Northwest can be as big as 1 meter across! The mouth of a sea star is found in the centre of the underside of the sea star (called the oral surface). Several rows of tube feet run from the mouth down each arm of the sea star. These rows of tube feet are guarded by movable spines that line the edges of the arms for protection. The back side of sea stars can be smooth, spiny, or slimy.
Movement:
Sea stars walk using their tube feet to move themselves along a surface. Their tube feet have suckers on the ends, which they use to attach themselves to rocks and to trap prey items. Sea stars that live on soft surfaces (such as sand) do not have suckers. These sea star uses their longer tube feet instead, to penetrate into the sand and other soft surfaces.
Feeding Habits:
Most sea stars are carnivores (which means that they eat other animals) that feed on gastropods, barnacles, sea anemones, sea snails, sea urchins, bivalves (shellfish) and some times even crabs, dead fish, and other sea stars. Pretty much any animal they can get their feet on! Instead of their food into their mouth as we do, sea stars instead flip their stomachs out through their mouth and digest their prey from the inside out. When the animal is completely digested the stomach is pulled back into the sea star's body.
Reproduction:
Sea stars are dioecious, meaning that the males and females are in separate individuals, and have as many as ten gonads (two at the end of each arm)! Sea stars reproduce by free spawning which means the eggs and sperm are released into the water from the male and female at the same time. The eggs and sperm then drift off until they meet up with each other and fertilization occurs. Hundreds of thousands of larvae are released into the ocean during one breeding season, however a large portion of these do not survive. As sea star larvae float along through the plankton they are food to fish and other sea creatures.
Regeneration:
Sea stars have the remarkable ability to regrow their arms if they are damaged or eaten by predators. In fact, in some cases an entire sea star can be regenerated from just a single arm! However, this process is slow and it may take up to a year for a sea star's arm to grow back to its original size.
Three common sea star species of the Pacific Coast are:
Dermasterias imbricata:
Common name: Leather Star
Alternate name: Garlic Star
Description:
The Leather Star is a slimy creature that can be up to 10 inches in size, most however are only 8 inches across. Leather stars are usually reddish brown in colour mixed with gray. Often times leather stars can be found with elements of purple between the red. This sea star has a strong garlic odour as its alternative name suggests.
Habitat and Distribution:
Leather stars live in rocky areas of the seashore from Alaska to California.
Other interesting facts:
Leather Stars cause an extreme response in the sea anemone, Red Stromphia. When the anemone feels the touch of a Leather Star, it immediately begins to sway back and forth until its base detaches from the sea floor. The anemone will "dance" through the water to distance itself from its enemy. Once it feels it is far enough away from the leather star, it will settle down on the sea floor once again.

Mediaster aequalias:
Common name: Vermilion Star
Alternate name: Equal-arm Star
Description:
Vermilion sea stars are bright red on their dorsal side (side facing the water) and are orange on the under side.
Habitat and distribution:
Equal-arm stars are found along the west coast of North America from Alaska down to California, on gravel, rocks, and sand in the low intertidal zone.

Starfish (more correctly known as sea stars as they are not related to fish) are marine invertebrates belonging to the phylum Echinodermata, class Asteroidea. The names sea star and starfish are also ...

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Starfish (more correctly known as sea stars as they are not related to fish) are marine invertebrates belonging to the phylum Echinodermata, class Asteroidea. The names sea star and starfish are also (incorrectly) used for the closely related brittle stars, which make up the class Ophiuroidea. They exhibit a superficially radial symmetry. Starfish typically have five or more "arms" which radiate from an indistinct disk (pentaradial symmetry). In fact, the evolutionary ancestors of echinoderms are believed to have had bilateral symmetry, and starfish do exhibit some superficial remnant of this body structure, which is evident in their larval pluteus forms.
Starfish do not rely on a jointed, movable skeleton for support and locomotion (though they are protected by their skeleton), but instead possess a hydraulic water vascular system that aids in locomotion. The water vascular system has many projections called tube feet, located on the ventral face of the starfish's arms, which function in locomotion and aid with feeding.
There are about 1,800 living species of starfish, and they occur in all of the Earth's oceans. The greatest variety of starfish is found in the tropical Indo-Pacific. Areas known for their great diversity include the tropical-temperate regions around Australia, the tropical East Pacific, and the cold-temperate water of the North Pacific (California to Alaska). Asterias is a common genus found in European waters and on the eastern coast of the United States; Pisaster, along with Dermasterias ("leather star"), are usually found on the western coast. Habitats could range from tropical coral reefs, kelp forests to deep-sea floor, although none of them live within the water column; all species of starfish found are living as benthos. Echinoderms need a delicate internal balance in their body, no starfish are found in freshwater environments.

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海星是棘皮动物门的一纲，下分海燕和海盘车两科，不过人们都俗称其为海星或“星鱼”。
海星主要分布于世界各地的浅海底沙地或礁石上，它对我们并不陌生。然而，我们对它的生态却了解甚少。海星看上去不像是动物，而且从其外观和缓慢的动作来看，很难想象出，海星竟是一种贪婪的食肉动物，它对海洋生 态系统和生物进化还起着非同凡响的重要作用。这也就是它为何在世界上广泛分布的原因。
人们一般都会认为鲨...

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海星是棘皮动物门的一纲，下分海燕和海盘车两科，不过人们都俗称其为海星或“星鱼”。
海星主要分布于世界各地的浅海底沙地或礁石上，它对我们并不陌生。然而，我们对它的生态却了解甚少。海星看上去不像是动物，而且从其外观和缓慢的动作来看，很难想象出，海星竟是一种贪婪的食肉动物，它对海洋生 态系统和生物进化还起着非同凡响的重要作用。这也就是它为何在世界上广泛分布的原因。
人们一般都会认为鲨鱼是海洋中凶残的食肉动物。而有谁能想到栖息于海底沙地或礁石上，平时一动不动的海星，却也是食肉动物呢！不过实际上就是这样。由于海星的活动不能像鲨鱼那般灵活、迅猛，故尔，它的主要捕食对象是一些行动较迟缓的海洋动物，如贝类、海胆、螃蟹和海葵等。它捕食时常采取缓慢迂 徊的策略，慢慢接近猎物，用腕上的管足捉住猎物并将整个身体 包住它，将胃袋从口中吐出、利用消化酶让猎获物在其体外溶解 并被其吸收。
我们已知海星是海洋食物链中不可缺少的一个环节。它的捕 食起着保持生物群平衡的作用，如在美国西海岸有一种文棘海星 时常捕食密密麻麻地依附于礁石上的海虹（谈菜）。这样便可以 防止海虹的过量繁殖，避免海虹侵犯其他生物的领地，以达到保 持生物群平衡的作用。 在全世界有大约2000种海星分布于从海间带到海底的广阔领 域。其中以从阿拉斯加到加利福尼亚的东北部太平洋水域分布的 种类最多。
海星与海参、海胆同属棘皮动物。它们通常有五个腕 但也有四六个，有的多达40个腕，在这些腕下侧并排长有4 列密 密的管足。用管足既能捕获猎物，又能让自己攀附岩礁，大个的 海星有好几千管足。海星的嘴在其身体下侧中部，可与海星爬过 的物体表面直接接触。海星的体型大小不一，小到2·5厘米、大 到90厘米，体色也不尽相同，几乎每只都有差别，最多的颜色有 桔黄色、红色、紫色、黄色和青色等。
在自然界的食物链中，捕食者与被捕食者之间常常展开生与 死的较量。为了逃脱海星的捕食，被捕食动物几乎都能做出逃避 反应。有一种大海参，每当海星触碰到它时，它便会猛烈地在水 中翻滚，趁还未被海星牢牢抓住之前逃之夭夭。扇贝躲避海星的 技巧也较独特，当海星靠近它时扇贝便会一张一合地迅速游走。 有种小海葵每当海星接近它时，它便从攀附的礁石上脱离，随波 逐流，漂流到安全之地。这些动物的逃避能力是从长期进化中产 生的。避免了被大自然所淘汰的命运。
尽管海星是一种凶残的捕食者，但是它们对自己的后代都温 柔之至。海星产卵后常竖立起自己的腕，形成一个保护伞，让卵 在内孵化，以免被其他动物捕食。孵化出的幼体随海水四外漂流 以浮游生物为食，最后成长为海星。
海星的经济价值不大，只能晒干制粉作农肥。由于它捕食贝 类，故而对贝类养殖业十分有害。

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