Shell ornamentation as a defensive structure

Shell ornamentation of marine calcifiers is considered as a potential anti-predatory defensive structure. We tested the hypothesis that the strength of brachiopod shell ornament treated as anti-predatory defence mechanism decreases with latitude and water depth. We found no statistically significant associations between ornamentation of living brachiopods and latitude or their ornamentation and water depth, a pattern sharply contrasting with that of most fossil brachiopods. Nearly 60% of living brachiopods are characterized by smooth shells. High proportion of smooth shells can be explained, among others, by their preference for cryptic and deep water habitats where the predation pressure is low.