Wrasse eats corals by Ôkiss­ingõ them

Practical Fishkeeping (UK) - - Fishkeeping News -

Of all the things an an­i­mal could eat, corals are ar­guably one of the tough­est, thanks to their thin, mu­cus-cov­ered flesh packed with ven­omous sting­ing cells spread over a ra­zor-sharp skele­ton. Per­haps that ex­plains why of the more than 6,000 fish species that live on the reef, only 128 are known to feed on corals.

Now, re­searchers have dis­cov­ered that at least one species of coral-feed­ing fish ‘kisses’ the flesh and mu­cus off the coral skele­ton us­ing pro­tec­tive, self-lu­bri­cat­ing lips.

“The lips are like the gills of a mush­room but cov­ered in slime,” says David Bell­wood of James Cook Univer­sity in Aus­tralia. “It is like hav­ing a run­ning nose but hav­ing run­ning lips in­stead.”

The re­searchers sug­gest that the mu­cus may fa­cil­i­tate suc­tion while of­fer­ing pro­tec­tion from the corals’ sting­ing ne­ma­to­cysts.

Wrasses that don’t eat corals have lips that are thin and smooth, with teeth that pro­trude slightly. By com­par­i­son, Tube­lip wrasses,

Labrop­sis aus­tralis, have lips that are fleshy and stick out, form­ing a tube when the mouth is closed that cov­ers all the teeth.

The most prom­i­nent char­ac­ter­is­tic of the Tube­lip wrasse’s lips, they found, are nu­mer­ous thin mem­branes ar­ranged out­wards from the cen­tre like the gills of a mush­room. The mouth sur­face also in­cludes many folds loaded with highly pro­duc­tive mu­cus-se­cret­ing glands. In other words, their lips drip with slime!

The wrasses feed by briefly plac­ing their lips in con­tact with the coral prior to de­liv­er­ing a pow­er­ful suck, ap­pear­ing to seal the mouth over a small area.

The new ev­i­dence sug­gests that the Tube­lip wrasse sur­vives by feed­ing pri­mar­ily on coral mu­cus.

A tube­lip wrasse wraps its slimy lips around a coral.

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