Department of Zoology at ANDC/Zoology Museum/Museum specimens/Hemichordata

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Phylum HemiChordata

Date & Time : 17, October 2017 06:11



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