Ecological Reasons for the Unusually High Rate of Gastropod Drill Hole Repair in the Deep‐Sea Brachiopod Abyssothyris wyvillei From New Zealand

Brachiopods are able to repair drill holes made in their shells by predatory gastropods. However, in most samples examined, drill hole repair is rare to absent: Presumably the drilling attack is usually fatal to the prey. The shells of short‐looped brachiopod Abyssothyris wyvillei , from deep‐sea dredge samples from two localities in the Tasman Sea, New Zealand, show both a high rate of drilling by muricid gastropods and an unusually high rate of drill hole repair, with some specimens having multiple repaired drill holes. Abyssothyris is one of the largest and most common bivalved organisms collected at the two stations. Examination of the molluscan taxa from the same samples revealed the presence of three species of muricid, one large and two small. The much higher number of muricid drill holes in Abyssothyris shells (129) than in molluscan shells (11) and the small size of the drill holes in Abyssothyris shells (0.15–0.8 mm) suggests that the two small muricid species targeted Abyssothyris as a preferred prey species. The majority of repaired drill holes occur over a smaller shell size range (0.15–0.5 mm), and statistical analysis shows this to be significant. This is interpreted as juvenile to young gastropods making successful drilling attacks on Abyssothyris but their appetite not being sufficient to inflict a mortal wound on their much larger prey, and the brachiopods are then able to repair the drill holes.