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  • José H. Leal

The Angel Wing and Its Siphons

Angel Wings (Cyrtopleura costata) live buried in sand or mud, inhabiting a cylindrical tunnel, which they occupy for the duration of their lives. Like most bivalve mollusks, Angel Wings are filter feeders, pulling water in through an incurrent siphon, pushing it through the gills, where the food particles are retained, then returning the water back to the environment via an excurrent siphon. The siphons are extensible, relatively long, and longitudinally fused. The incurrent siphon is wider than the excurrent one.  

Cyrtopleura costata. Incurrent (wider) and excurrent siphons. Photo by Amy Tripp at Kice Island, Florida.

The illustration above, taken by Amy Tripp at Kice Island, Florida, shows the siphons protruding from the sandy bottom. And the short video below, by Linda Shockley, shows the two siphons “in action”, with the current released by the excurrent siphon noticeably reaching the water surface above it. Many thanks to Linda and Amy for letting me use their materials in this post!

Cyrtopleura costata. Video of the siphons "in action" by Linda Shockley.

Cyrtopleura costata. Shell from Captiva Island, Florida. Illustration by James F. Kelly.


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