Juvenile Urchin ID

[kidspot]

Sorry for the fuzzy photo (just could not get the camera to focus down that "hole"), but I've seen 2 of these this week and can't tell if they are juvenile Slate Pencil or Rough Spined Urchins. Anyone know which this is? The spines are rough looking but the only mature urchins in the area are the Slate Pencils.

Aloha, Tim

 

[VBlueV]

it looks like a "ten-lined/sputnik" urchin.. :biggrin3:

from keoki's site:
Sea Urchins

 

[archman]

I do not know the scientific name for "rough spined urchin".

That IS a cidaroid urchin, which includes the "slate pencils" in the genus Eucidarus.

The animal in the pic is NOT a Heterocentrotus. Wrong family.

 

[kidspot]

JJ - thx for the ID - for some reason I thought the 10-Lined were a lot bigger than that. These were only an inch or so across which led me to think they were juveniles.

Archman - Scientific name for rough spined is Prionocidaris hawaiiensis according to the link JJ posted above.


Mahalo, Tim

 

[archman]

It should be noted that both the "rough spined urchin" and "ten-lined urchin" are commonly referred to as "slate pencil urchins" as well. Neither is more or less correct than the other.

"Slate pencil" urchins comprise multiple related and unrelated species, genera, and families throughout the world's oceans. Basically, it applies to any urchin with very thick, blunt primary spines.:11:

 

[kidspot]

How do you differentiate between the different "Slate Pencil" urchins? Local common names or is there another way?

 

[KrisB]

Just to add to the mix... any chance it's "Thomas's Urchin" (Hoover, p 310-311)?

I think by "slate pencil urchin" we usually mean the "Red Pencil Urchin" (Heterocentrotus mammillatus, Hoover p.317-318) around here...

 

[archman]

Cidaroid urchins are very distinctive. Large, widely spaced primary spines, and very teeny secondary spines. Unlike other urchins, cidaroid spines aren't coated in a thin living tissue layer. Thus the spines may look "ratty". No external gills on cidaroids either.

If you're not a cidaroid urchin, you're everything else.

 

[blesi varney]

I also think it is Thomas's urchin.

 

[howard4113]

Tim,

Here's a technique that might help in the future. Most cameras will lock focus if you press the shutter halfway. So just point the camera at something that's the same distance away as the subject and press the shutter halfway (your cam probably has a focus lock light to tell you when it's got a fix). Then point the cam at the subject using the same distance that it's locked to -- and fire away.

Hope this helps,
M