#pteropod

The Devil Inside

Remember our adorable little friend, the sea angel (Clione limacina)?

This is the sea angel in hunting mode.

When feeding and hunting, C. limacina can rapidly shoot out three pairs of buccal cones which latch onto its prey (and fellow pterapod), the sea butterfly. These cones are lined with adhesive ridges and excrete a viscous material that help prevent the sea butterfly from escaping.

Then, as C. limacina holds the captured sea butterfly in front of its mouth, it uses specialized hooks to extract its prey’s soft parts to be devoured. Mmmm…heavenly! 

 Image source: Alexander Semenov

Reference:Hermans and Satterlie. 1992.

Armored ‘Flight’…?

Like its fellow pteropod the sea angel, the sea butterfly(Limacinahelicina) is a 'wing-footed’ pelagic gastropod that spends its time fluttering about in the water column. 

But unlike the sea angel, the sea butterfly is equipped with a tiny shell. This shell is among the thinnest recorded for shelled gastropods: shells measuring 0.5–6 mm in diameter are only 2–9 μm thick! Yes, their shells are just a thousandth of a millimeter thick.

The thinness of the sea butterfly’s shell makes its function in defense doubtful. However, this lightweight shell has allowed L. helicina to take to the 'skies’ (or rather, the water column)—a way of life denied to its more heavily-armored, bottom-dwelling cousins, the sea snails. 

Image source: Alexander Semenov

Reference:Sato-Okoshi et al.2010.