|
Date & Time : 22, December 2024 17:47
General Characteristics of HemiChordata
Classification of HemiChordata
A Few Examples
1. Balanoglossus
Common name: Acorn worm
Geographical distribution: Cosmopolitan or world–wide
Habitat: Marine burrowing, worm-like
Characteristic Features:
1. Body: soft and cylindrical having ciliated surface
2. Body Length: 10-50 cm long
3. Body division: short conical proboscis, collar and long trunk
4. Cavity of proboscis opens to exterior by a proboscis pore. Proboscis has thick muscular walls
5. Short, muscular cylinder-like collar encloses cavity (collar coelom) which open on the dorsal surface by a pair of collar pores
6. Superficially ringed trunk (devoid of segmentation)
7. Trunk divided into anterior branchio-genital region, a middle hepatic region and a posterior abdominal region
8. The branchio-genital region has a pair of genital wings formed by internal gonads and a branchial groove having numerous paired gill-slits arranged in 2 rows
9. The hepatic region has double rows of hepatic caecae
10. Straight alimentary canal
11. Anus is present on posterior end of body
12. Sexes separate
13. Fertilization external
14. Development includes free-swimming pelagic Tornaria larva
|
