Common or Not?

[swfishguy]

I have a spiny sea cucumber(Colochirus sp) that doesn't extend it "tentacles" out fully. He just keeps them halfway out then sometimes he just close back up fully. Here is an image:

The location he is in is a good place because it likes a funnel effect that goes through the rock work.

 

[bang guy]

It should extend fully once it detects food in the water. I'm not familiar with this Cucumber but I would be very careful. It's a filter feeder and therefore likely to be very toxic to vertebrates if disturbed. It probably can eat things like oyster eggs but to be honest I'm not really sure what that species would eat.

 

[swfishguy]

I got it from another site and here is the description of it:
Care Level: Moderate
Reef Compatible: Yes
Diet: Detrivore
Range: Indo-Pacific
Family: Cucumariidae
Water Conditions: 74-80° F; sg 1.023-1.025; pH 8.1-8.4; dKH 8-12
Notes: A colorful and bizarre addition to any reef aquarium, the Spiny Sea Cucumber can live for many years in the home aquarium. It will move around the aquarium until it finds an area with a good current where it can filter plenty of food. Once it finds a desirable spot it may stay there for many months.
The Spiny Sea Cucumber uses its oral tentacles to catch food that floats by. As each tentacle becomes full of food it draws its entire tentacle into its mouth. It must be fed foods for filter feeders including marine snow, phytoplankton, and zooplankton. If not properly fed the body of the Spiny Sea Cucumber will slowly begin to shrink.
The Spiny Sea Cucumber can be harmed by the intakes of any pumps or powerheads in the aquarium, so make sure to protect all intakes to prevent it from being sucked in.
I do feed him phyto, when I feed my corals. He just retracts usually.
I also think it goes by the name pink cucumber. I am not 100% on that.

 

[bang guy]

I'm out of my league with this Cucumber but I strongly doubt that it's a detrivore as indicated. I'm also not sure phytoplankton will nourish it. There's certainly room for me to be wrong but my guess is that it needs zooplankton. Time will tell. The description is correct that Sea Cucumbers shrink when malnourished so you will know if it's getting enough to eat.

 

[swfishguy]

This is what I am using to feed it and my corals:
http://brightwellaquatics.com/products/phytogreenm.php

 

[bang guy]

Mostly, only soft corals can eat that. If you're trying to feed hard corals then zooplankton is a better fit.
If you have a clam then it's good for that. Pods as well as tube worms can also eat it.