Tamm, S. L., & Tamm, S. 1991. Reversible epithelial adhesion closes the mouth of Beroe, a carnivorous marine jelly. The Biological Bulletin, 181: 463-473.

To facilitate engulfment-based feeding on other ctenophores, comb jellies of the genus Beroe have unusually large mouths. These mouths constitute a significant proportion of the Beroe's body, and must be closed quickly and kept shut following ingestion of prey to maintain a streamlined form while swimming. The ability to close their mouths and maintain closure during swimming is an essential ability, but how does Beroe do this?

Beroe with thin body walls were collected from locations in Massachusetts and California, and then observed by either video camera recordings or electron microscopy. Mouth-opening responses of the ctenophores were induced by placing food in close proximity to the ctenophore followed by video recording, while electron microscopy was conducted on tissue samples prepared from the closed mouths of the Beroe. The authors found that mouth closure occurred automatically without any neuromuscular activity, and paired strips of adhesive epithelial cells facilitated reversible adhesion between the lips. Opening of the mouth involved neuromuscular action, and was characterized by the peeling apart of the epithelial strips starting at a single point of high muscular tension.

The adoption of adhesive epithelial strips for mouth closure bypasses the need for neuromuscular activity, while peeling apart the lips upon opening minimizes necessary muscular tension for opening. These adhesive relationships between cells closely mirror those found between many cultured and embryonic cells, and hence may hold promise for investigating these adhesive mechanisms further.

(236 words)

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(posted Dec. 24 2015)