Browsing by Author "Davenport, John"
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- Digging with 'hands': observations of food capture in the flying gurnard Dactylopterus volitans (Linnaeus, 1758)Publication . Davenport, John; Wirtz, PeterVideofilms of a foraging flying gurnard (Dactylopterus volitans) were collected at Itaipu, Niteroi, RJ, Brazil. Analysis revealed details of the use of anterior parts of the pectoral fins which act as digging 'hands' to access infaunal prey items that are subsequently captured by oral suction feeding. Each pectoral fin has two distinct sections articulated separately on the pectoral girdle. The digging 'anterior pectoral fin' mainly consists of segmented and flexible fin rays but has an anterior robust unsegmented ray that provides an edge to the 'hand', allowing penetration of the substratum. The huge 'posterior pectoral fins' are supported by unsegmented rays. Most digging episodes involved one 'hand' and consisted of 1-7 cycles of movement with frequencies 1.15-3.74 cycles s(-1). During a cycle, the 'hand' is moved forwards and medially above the substratum, then is twisted medially and simultaneously depressed so that the anterior unsegmented ray impacts and enters the substratum. The hand is then drawn backwards and laterally to disturb the substratum. To prevent upward pitching of the head during digging, the 'posterior pectoral fins' are both moved anteriorly and laterally to shift the centre of gravity forwards while the caudal and second dorsal fins continue to provide propulsive force.
- Further investigations on fincrawling in flatfishes (Teleostei: Pleuronectiformes): phylogenetic implicationsPublication . Wirtz, Peter; Davenport, John; Chanet, BrunoFincrawling is a unique, recognizable behaviour pattern exhibited by many flatfishes (order Pleuronectiformes), whereby the fish uses the fin rays of the dorsal and anal fins to walk over the substratum. The distribution of this behaviour among flatfishes indicates it appeared early in the phylogeny of the Pleuronectiformes. Fincrawling is a common character of the Pleuronectoidei, and a possible synapomorphy of the suborder.