Class of Phylum Echinodermata
Bipinnaria & Brachiolaria
Dobolaria & Pentacrinoid
- It is a bilaterally symmetrical free swimming pelagic larva.
- The pre-oral region is elongated. Post-oral region is broad. The anterior end forms pre-oral lobe.
- Ventro-median arm.
- A pair of pre-oral arm.
- Median dorsal arm.
- A pair of antero-dorsai arm.
- A pair of posterio-dorsal arm.
- A pair of posterio-lateral arm.
- A pair of post oral arm.
- The digestive system is developed with mouth and anus. This larva resembles Tomaria larva of Balanoglossus.
- It is bilaterally symmetrical larva.
- It is pelagic larval form, it shows 3 brachiolar arms with suckers. They are one median and two lateral in position.
- At the tip of brachiolar arms adhesive structures will make their appearance and they are for attachment.
- The larva shows all the arms that areseen in the Bipinnaria, but these arms are very long and hanging. These ciliated arms will be helpful for swimming in the water.
- The digestive system is completely developed with definite stomach and intestine.
- It is a free swimming pelagic larva.
- Arms are absent. Alimentary canal is developed. It opens with mouth and ends with anus.
- Intestine is curved.
- In Japan and Bermuda very big auricularia larval forms are developed. They are 15 mm in length. Usually this larva is 1 mm in length.
- Ciliated bands are well-developed. Ciliated band continues through oral loop and anal loop.
- It is a microscopic larva.
- It swims in water.
- This larva shows ciliated bands which are developed into arms.
- Fully developed echinopluteus larva 4 or 5 pairs of arms are present. Usually 6 pairs of arms should be resulted.
- The arms are supported by (CaCO3) Calcareous rods.
- The digestive system is developed which shows mouth and anus.
- It develops hydrocoel and vestibule. These parts grow on the oral side of the animal. From the hydrocoel five radial canals will develop.
- It is a free swimming larval form.
- It contains an apical tuft of cilia which will be sensory.
- On the mid ventral line near apical plate adhesive pit will be present.
- The body shows 4 or 5 ciliated bands
- In between 3rd and 2nd ciliated bands vestibule is present.