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Crinoid

Crinoidea

Description:

Saw this Crinoid spawning during a night dive. First time to see this after 12 years of diving. The tiny pink stuff are the eggs/sperm (spawn). The black thing 'sitting' on the coral is the Crinoid. Our dive lights attracted small shrimps and they were following us during our dives and when we shine our lights on this spawning Crinoid, it looks like the small Shrimps are feeding on them. Please watch the video to fully appreciates this Spotting. Crinoids are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". Crinoids are characterised by a mouth on the top surface that is surrounded by feeding arms. They have a U-shaped gut, and their anus is located next to the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, most crinoids have many more than five arms. Crinoids usually have a stem used to attach themselves to a substrate, but many live attached only as juveniles and become free-swimming as adults. There are only about 600 extant crinoid species, but they were much more abundant and diverse in the past. Some thick limestone beds dating to the mid- to late-Paleozoic are almost entirely made up of disarticulated crinoid fragments. Crinoids are dioecious, with separate male and female individuals. They have no true gonads, producing their gametes from genital canals found inside some of the pinnules. The pinnules eventually rupture to release the sperm and eggs into the surrounding sea water. The fertilised eggs hatch to release a free-swimming vitellaria larva. The larva is barrel-shaped with rings of cilia running round the body, and a tuft of sensory hairs at the upper pole. In some cases females have been known to temporarily brood the larvae using chambers within the arms. While both feeding and non-feeding larvae exist among the four other extant echinoderm classes, all present day crinoids appears to be descendants from a surviving clade that went through a bottleneck after the Permian extinction, which had lost its feeding larval stage. The larva's free-swimming period lasts only for a few days before settling to the bottom and attaching itself to the underlying surface using an adhesive gland on its ventral surface. The larva then metamorphoses into a stalked juvenile. Even the free-swimming feather stars sometimes go through this stage, with the adult eventually breaking away from the stalk. Within 10 to 16 months the crinoid will be able to reproduce.

Habitat:

They live both in shallow water and in depths as great as 6,000 metres (20,000 ft). Sea lilies refer to the crinoids which, in their adult form, are attached to the sea bottom by a stalk.

Notes:

Watch video from this link https://www.youtube.com/watch?v=Y6hiqqVx...

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5 Comments

ChunXingWong
ChunXingWong 8 years ago

Your spotting has been nominated for the Spotting of the Week. The winner will be chosen by the Project Noah Rangers based on a combination of factors including: uniqueness of the shot, status of the organism (for example, rare or endangered), quality of the information provided in the habitat and description sections. There is a subjective element, of course; the spotting with the highest number of Ranger votes is chosen. Congratulations on being nominated!

Leuba Ridgway
Leuba Ridgway 8 years ago

Great spotting. Thanks for the video Albert.

Mark Ridgway
Mark Ridgway 8 years ago

What a sight!

AlbertKang
AlbertKang 8 years ago

Thanks, @Ava, glad you like this one :)

Ava T-B
Ava T-B 8 years ago

Albert, what an amazing spotting. The video really does make it come alive, and your notes are great.

AlbertKang
Spotted by
AlbertKang

Batangas, Philippines

Spotted on Jan 31, 2016
Submitted on Feb 1, 2016

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