On the first episode of BBC's Blue Planet II they visited a coral reef and showed some odd reef-dwelling creatures as part of their establishing shots, but they did not identify the creatures.

What is this odd horned, slug-like creature? (Sort of like a slug with legs?)

Sea Blob

I tried a Google reverse image search and it very 'helpfully' identified it as "Documentary film". So close, yet so far.

Disclaimer: This question was split off from another question since the original was effectively two questions.

  • $\begingroup$ I think the OP might be referring to the black leg like things at the front. These are feeding tentacles according to Wikipedia. The tube legs are the short stubby things along the underside. I ended up here wondering about this too - thanks! Great show :) $\endgroup$
    – Phil
    Commented Mar 11, 2018 at 20:08

1 Answer 1


Here is your animal in Blue Planet II trailer:

enter image description here

This is a sea cucumber (Phylum Echinodermata, Class Holothuroidea).

More specifically, this is a sea cucumber from the Species Pearsonothuria graeffei, the Graeffe's sea cucumber.

Here are other images of Pearsonothuria graeffei for comparison:

enter image description here

enter image description here

Sea cucumbers have an antero-posterior elongated body, as you can see in this image of the whole animal:

enter image description here

Those black structures you see are the tube feet, a distinctive feature of Echinoderms.

Here is a detailed image of the tube feet in Pearsonothuria graeffei:

enter image description here

  • $\begingroup$ Thank you for the interesting answer. I now realise that they did identify it later on, but from a different camera angle where the body was hidden and only the mouth was shown so I didn't make the connection. The sea cucumber is a strange animal indeed. $\endgroup$
    – Pharap
    Commented Nov 9, 2017 at 22:12
  • 1
    $\begingroup$ @Pharap Good to know. I didn't see Blue Planet II yet, but I will, I'm a huge fan of Attenborough. $\endgroup$
    – user24284
    Commented Nov 13, 2017 at 12:25

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