PPT Slide
- Most primitive of the echinoderms
- Unusual in that the oral surface is directed upward
- Aboral surface is attached to the substrate by means of a bendable stalk
- The portion of the crinoid body attached to the stalk is called the crown; bears a number of arms
- Along the length of the arms are branches called pinnules
- The arms and the pinnules have ambulacral grooves with suckerless podia (secrete mucus)
- The ambulacral grooves are heavily ciliated and the cilia is used to direct food to the mouth (=filter feeding)