线虫主要特点
1.形态 2.成虫圆柱形,两侧对称,线状,不分节 3.雌雄异体。♀大♂小, ♂虫尾端多向体腹面卷曲或膨大。 4.体壁结构: 5.原体腔:在体壁与消化管之间的腔隙,因无体腔膜覆盖,故称为原体
腔(primary coelom) 6.体壁:自外向内由角皮层、皮下层和纵肌层组成 7.内部器官: 8.消化系统简单,有口→咽→中肠→直肠→肛门 9.生殖系统发达,管状结构,雄虫属单管型,雌虫属双管型 10.生活史分为直接发育型和间接发育型 11.基本过程分虫卵、幼虫和成虫三阶段 12.幼虫发育最显著特征是蜕皮(molting),一般蜕皮4次
host
Nematode development is similar in all nematodes.
Consists of 4 larval (=juvenile) stages between the egg and adult. Each stage is separated by a molt of the cuticle.
M1
M2
M3
M4
Egg
L1
L2
L3
L4
Adult
Larval stages may be passed within the egg, free-living in soil, parasitic in an intermediate host, or parasitic in definitive host.
acre in good farmland • Parasitic infections can
be enormous
Phylum Nematoda
• More species than any other phylum