Relationship between morphology and diets of six neotropical loricariids

Abstract

Most loricariids are algivorous and detritivorous and play an important role in both the grazer and detritus food chains of neotropical waters. Relationships between morphological variation and diet were analysed in six syntopic species (Rhinelepis aspera, Hypostomus regani, H. ternetzi, H. margaritifer, H. microstomus and Megalancistrus aculeatus) fished commercially in a 10 km 2 area of the Upper Paraná River upstream from the Itaipu Reservoir. Species feeding on fine grained detritus use suction to obtain food, and possess a well-developed respiratory membrane, long gill rakers, rudimentary labial and pharyngeal teeth, a thin stomach wall, and a long intestine. Species feeding on coarser material (e.g. periphyton), ingest food by scraping the substratum. Their morphological characteristics are large, strong, spatulate teeth, short gill rakers, a well-developed stomach, and a shorter intestine. The first species group is composed by R. aspera while the latter by M. aculeatus and H. microstomus. The others species had an intermediary position. 2001 The Fisheries Society of the British Isles

Gill rakers in six teleost species: influence of feeding habit and body size

“…This characteristic indicates a strategy for the protection of these structures (EIRAS-STOFELLA & CHARVET-ALMEIDA, 1997). The same pattern was found by DELARIVA & AGOSTINHO (2001) in other species of detritivorous fi shes. However, Table 1 -Relationships between fish length and gill raker length and between fish length and distance between gill rakers.…”

“…In planktivorous and detritivorous fi shes, the gill rakers are numerous, fi liform and near each other, functioning as an effi cient fi lter (DELARIVA & AGOSTINHO, 2001;RODRIGUES et al, 2006). These structures become increasingly complex as the fi sh grows, with a signifi cant increase of gill rakers and development of spines (ROSS et al 2006).…”

“…Previous studies analyzed gill rakers and their adaptations related to feeding in species with the same feeding habit (LANGELAND & NØST, 1995;EIRAS-STOFELLA & CHARVET-ALMEIDA, 1997) or related gill rakers to species identifi cation (LUCENA et al, 1992). Most previous studies addressing digestive tract structure did not describe the gill rakers in detail.…”

Morphological variability of the shape of striped red mullet Mullus surmuletus in relation to stock discrimination between the Bay of Biscay and the eastern English Channel

“…surmuletus in the eastern English Channel and southern North Sea is higher than those observed in southern areas. Feeding behaviour is a well‐known factor that influences head morphology (Hyndes et al , ; Delariva & Agostinho, ; Palma & Andrade, ; Silva, ; Janhunen et al , ) and an organism's somatic growth (Loy et al , ). Thus, fish trophic ecology might be one of the principal explanatory factors for morphological divergences observed in this study.…”

Morphological variation in head shape of pipefishes and seahorses in relation to snout length and developmental growth

“…In most animals, jaw morphology, mouth shape, and dentition type can provide a quite accurate idea about the preferred prey type and feeding strategy. The shape of a fish skull, consisting of over 30 moveable bony elements and more than 50 muscles (Lauder,1983), reflects the individual's diet and prey capture mechanism to a great extent (Gerking,1994; Delariva and Agostinho,2001; Ferry‐Graham et al,2001; Palma and Andrade,2002). Dietary influences on head morphology (or vice versa) are particularly evident in trophic specialists, who exploit a limited dietary breadth with respect to the available prey types in their habitat (Sanderson,1991).…”