国产热热热精品,亚洲视频久久】日韩,三级婷婷在线久久,99人妻精品视频,精品九热人人肉肉在线,AV东京热一区二区,91po在线视频观看,久久激情宗合,青青草黄色手机视频

您現(xiàn)在的位置: > Language Tips > Easy English > Odd Question  
 





  What creatures have four kinds of legs?
[ 2006-03-14 08:38 ]

Decapod crustaceans (1) (shrimps, crayfish (2), and lobsters (3)) have 14 pairs of "legs", divided into four different groups.

The first three pairs, just behind the animal's mouthparts (4), are "eating legs" (maxillipeds (5)), used to manipulate food before passing it forward to the mouthparts. They are usually hidden beneath the head/thorax shield (6) (carapace).

Next are five pairs of "walking legs" (pereopods (7)). In some crustaceans, the first pereopod is equipped with a large claw (8). Some pereopods have gills (9) attached near their bases.

Behind these are five pairs of "swimming legs" (pleopods (10)), used for swimming slowly forward. Some crustaceans carry their eggs among their pleopods.

Finally, there is one pair of "tail legs" (uropods (11)) that are part of the tail fan, which is used for sudden backwards flight from predators (12) and other potential threats.

(1) 十足甲殼類
(2) 小龍蝦
(3) 龍蝦

(4) (昆蟲等的)口器
(5) (甲殼動物的)顎足,(昆蟲)顎肢
(6) 頭胸甲


(7) 甲殼動物的胸部附器
(8) 鉗,螯
(9) 腮


(10)腹肢


(11)尾肢
(12)掠食者

 
 
 




玉林市| 庆云县| 北京市| 祁连县| 湛江市| 东平县| 治多县| 石门县| 台北县| 文登市| 宝鸡市| 徐闻县| 新营市| 东阳市| 大足县| 南和县| 西华县| 略阳县| 黄浦区| 湘阴县| 陕西省| 抚宁县| 讷河市| 进贤县| 汕尾市| 迁安市| 永城市| 毕节市| 阿瓦提县| 浦东新区| 泌阳县| 博爱县| 韶关市| 永顺县| 金塔县| 湟中县| 庄浪县| 噶尔县| 刚察县| 安宁市| 修文县|