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May 13 2013

Mary’s Monday Metazoan: I’m guessing uncircumcised

But that membrane hanging off of it is just plain weird.

caecilian

Maybe the video will help make sense of it all.

(via ZooBorns)

11 comments

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  1. 1
    Woo_Monster, Sniffer of Starfarts

    Somebody get this creature some beads.

  2. 2
    Kagato

    I discovered these things myself just a few days ago, when I was looking for example animals a creationist would have a hard time correctly placing into its “kind”, over in the Comfort thread.

    No doubt there are numerous examples, but mine all ended up snake-like. Caecilians were the most surprising (to me) in my list.

    Those toads, though. They’re freaky. And not just for their appearance.

  3. 3
    Ichthyic

    As to why the toads didn’t eat them…

    I guess they never heard that you’re never supposed to try and match wits with a Caecilian…

  4. 4
    ChasCPeterson

    caecilians: awesome!
    Whereas we mammals suckle our young on liquid secretions from modified skin glands, they feed their young chunks of their own skin.
    Those exernal gills are a nice touch indeed, tying them ostensibly to caudates/urodeles/salamanders unless DDMFM corrects me forthwith.

  5. 5
    Azkyroth Drinked the Grammar Too :)

    And remember, never go in against a caecilian when death is on the line!

  6. 6
    David Marjanović

    caecilians: awesome!

    *nodnod*

    Those exernal gills are a nice touch indeed, tying them ostensibly to caudates/urodeles/salamanders unless DDMFM corrects me forthwith.

    Well, the “internal” gills of tadpoles are actually external, too*, they just happen to have a gill lid** growing over them. Both morphology and (usually) molecules (these days) support a sister-group relationship between frogs and salamanders to the exclusion of caecilians.

    * External gills grow from the septa to which the internal ones are (otherwise) attached. In other words, each external gill lies between the places where two internal ones would be.

    Lissamphibian monophyly is pretty much consensus nowadays (the Anderson lab gave up their opposition last year), but external gills are a trait retained from a more distant ancestry: they’re shared by the larvae of temnospondyls and seymouriamorphs*. In other words, we are descended from ancestors whose larvae had external gills, too.

    * Fossils of larvae of other Paleozoic tetrapod-sensu-lato groups with soft-tissue preservation aren’t known.

    South American and African lungfish have external gills as larvae, too. But those grow from a different part of the septum and are lacking in their common sister-group, the Australian lungfish, so they’re probably not homologous to those of tetrapods.

  7. 7
    David Marjanović

    ** The gill lid of tadpoles may well be homologous to the usual osteichthyan gill lid, except that the bones in it are gone since Tiktaalik. A soft-tissue gill lid may also be preserved in the aquatic temnospondyl Isodectes, which apparently exchanged its external gills for internal ones later on, and shelves on the shoulder girdle bones against which a gill lid could close are present in many early tetrapods including close relatives of Isodectes.

  8. 8
    anchor

    geez and wow…like I’ve always said, WE are the aliens. (Earth critter=’we’)

  9. 9
    Sili

    It’s an angel! Praise JEEBUS!

  10. 10
    souhjiro

    well, the single pair of leaf-like external gills are different of the many pairs of filamentous, branched ones in urodela+caudata. Looks superficially very similar to the(pectoral fins derived)”gills” in the very derived fish Symbranchus marmoratus larva.

  11. 11
    souhjiro

    and… how do you do italics text in the comments?

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