Related to the Sand Dollar? & Odd Urchins?

[lanwu]

Location for both: Thailand Gulf off Koh Samet, close to Pattaya
Habitat for both: Sandy bottoms

These one's are like urchins but not round??
Purple one's size: about 8 cm
Yellow one's size: about 5 cm
I was guessing that the empty shells are from the matching species.

This big thing's like a cross between a Sand Dollar & a Starfish...anyone know exactly what it is...never seen it in any books.
Size: about 1 foot in diameter

 

[justleesa]

Not 100% sure but to me they look like different phases of the same type of urchin. The purple one being the most freshest (dead) and the white one with out the spines the oldest (all bleached out).

The name escapes me right now. It lives under the sand (stream lines spines to move thru the sand) and Horned Helmets dine on them.

 

[redrover]

These guys are pretty new to me – the ones here are hidden in the sand (and I was thrilled to find a similar test Wed.) but I’ll guess they are, or what I’d call an urchin. Looking in Tropical Pacific Invertebrates Page 258 (all I have at the moment) could be,

• Metalia sp. Spatangidae Echionidea (Phillipines)
• Sure looks like ‘an unidentified irregular urchin’ (LOL) “appears close to Maretia” (planulata) (Palau, Lighthouse Reef)
• a Brissus lacarinatus Brissidae test (Indonesia) “this is a large species of heart urchin reaching about 5” in length.”

the 1’….hmmm pretty big. Your post details are confusing to me. Both, 1’, this one and 4 pictures.....maybe this will give you some where to start.

 

[lanwu]

These guys are pretty new to me – the ones here are hidden in the sand (and I was thrilled to find a similar test Wed.) but I’ll guess they are, or what I’d call an urchin. Looking in Tropical Pacific Invertebrates Page 258 (all I have at the moment) could be,

• Metalia sp. Spatangidae Echionidea (Phillipines)
• Sure looks like ‘an unidentified irregular urchin’ (LOL) “appears close to Maretia” (planulata) (Palau, Lighthouse Reef)
• a Brissus lacarinatus Brissidae test (Indonesia) “this is a large species of heart urchin reaching about 5” in length.”

the 1’….hmmm pretty big. Your post details are confusing to me. Both, 1’, this one and 4 pictures.....maybe this will give you some where to start.

Hi RedRover,

I edited my descriptions....but sorry, wasn't sure which species to match w/ of your descriptions. Could you clarify ...maybe by color since there's 3 species (brown, purple & yellow). Thanks...

 

[justleesa]

Looked at your pics again and the last one is something totally different than the first 3.

John Hoover has a pic on his website of a simular one to the first 3 pics

 

[Rick Murchison]

This one

is a Pacific variety of what we call a "Sea Biscuit"... common over in the Caribbean.

This one...

is a great big sand dollar. Probably close kin to the Notched Sand Dollar common in the Caribbean.

The other two... are so far from radial symmetry that I'd really like to get my hands on a specimen to see what in the world we have here!
Rick

 

[sarita75]

Very pretty ..... in a hairy kinda way

 

[drbill]

#1 and #2 are heart urchins (also known as sea biscuits or sea mouse) and #4 a sand dollar. Although I've dived in the Gulf, I don't remember much about soft bottom species since I spent most of my time over the coral reefs. #3 I have no idea on.

 

[redrover]

As best as I could gather according to that book, the first three were Hearts and no mention of the last that looked like a dollar to me as well. Try looking up the names online and see if you can verify or define, and they are all urchin – it is my guess but this book is not consistent, nor ample in notes regarding the photos.
Hawaii has them but I’ve yet to see a live one (like any of yours) so done little looking up this type of critter. I could be wrong but I think they all are the burrowing in sand kind of urchin and rare find in the open. Pretty cool finds I think. If you took the test, I hope it made it home in one piece. I was amazed I got the test I found this week just up on the boat intact.

 

[Rick Murchison]

Found a positive ID on the Sand Dollar... Echinodiscus auritus - Two Slit Sand Dollar.

Rick