Explain about the terms - bursae and captacula?
Paired water-filled sac located at base of each arm of a brittle star. Cilia in bursae circulate water. Its surface is significant in gas in gas exchange. Gametes may also be released into the bursa.
Specialized ciliated tentacles that scaphopod molluscs use for feeding. Food is trapped on sticky bulb at the tip of captaculum before being moved to mouth by cilia on the captacula.