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

From WikiEducator
Jump to: navigation, search

Phylum Cephalochordata

Date & Time : 19, November 2017 01:25



General Characteristics of Cephalochordata

Classification of Cephalochordata

A Few Examples

1. Amphioxus

Geographical distribution: World -wide in distribution, found on the shores of all continents and many oceanic islands

Habitat: fish-like burrowing marine animal

Characteristic Features:

1. Body: enlongated, laterally compressed and pointed at both the ends

2. Body length is approx. 5 cm

3. Anterior end of body projected forward which is called rostrum

4. Low and continous fins - three types:

    a) dosal fin

    b) ventral fin

    c) caudal fin

5. Two metaneural folds

6. Myotomes are present on both sides and separated by v-shaped connective tissue, the myosepta or myocommata

7. Mouth is ventral to rostrum and guarded by oral hood bearing oral cirri

8. Atriopore is median and ventral and present at the junction of metaneural folds and ventral fin

9. On the left side a short distance in front of the posterior end anus is present

10. 26 pairs of gonads are present and arranged metamerically arranged on both sidesof the pharynx

11. Sexes separate but can't be distinguish externally