I found this creature on the beach in San Diego. It is 8cm long and the end to the right is the mouth. The underside is exactly the same as what is visible. enter image description hereWhat is the name of this species.


1 Answer 1


This animal is a sea cucumber. It is probably a "sweet potato" sea cucumber (Molpadia arenicola). Here is a useful link describing this animal with pictures quite similar to yours: https://mexican-fish.com/sweet-potato-sea-cucumber/

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    $\begingroup$ Welcome to Biology.SE! You are more likely to get a positive response to your answer if you explain why your identification is correct. Specifically, please edit your answer to add discussion of key features that led you to this conclusion and supporting references or at least validated images. Without this your answer is indistinguishable from opinion. ——— Please take the tour and then consult the help pages for additional advice on How to Answer effectively on this site. Thank you! 😊 $\endgroup$
    – tyersome
    Commented Jul 18, 2020 at 4:37
  • $\begingroup$ @tyersome I have a question about the accepted behaviour in this site. If an answer is correct but very short like this one are we supposed to edit the answer with photos and references or should we write a new answer? $\endgroup$ Commented Jul 18, 2020 at 5:20
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    $\begingroup$ @trinitrotoluene — I'm not sure there is a clear standard, but anything that results in a better answer is good. Constructive editing is always acceptable (and your suggestions will be reviewed). I would personally give the original answerer a day or so to respond and then post a better supported answer if they don't. You could also ask about the etiquette for this in the Biology Chat or post a question on Biology Meta. I had a quick look in the latter and didn't find anything related, but I could easily have missed something ... $\endgroup$
    – tyersome
    Commented Jul 18, 2020 at 20:07
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    $\begingroup$ @tyersome thank you for the insight. This was the most relevant answer i could find on meta. It seems it is best to discuss such changes with op in comments before editing. $\endgroup$ Commented Jul 18, 2020 at 20:25
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    $\begingroup$ @trinitrotoluene For an answer as short as this one, don't feel bad about adding a proper separate answer that includes citations and an explanation. For a longer answer that's just missing a citation you could comment or edit first, but it's also not a problem to write a new answer. We expect most answers here to be cited (some very basic biology that you would find in a "bio 101-like" freshman textbook probably doesn't need a citation, but I usually add a note to answers of mine like that to check a basic textbook, or at least link to wikipedia). $\endgroup$
    – Bryan Krause
    Commented Jul 23, 2020 at 1:03

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