Intestine Morphometrics of Fishes: A Compilation and Analysis of Bibliographic Data

Abstract

In fishes, both external (e.g., shape, size and position of mouth, shape of caudal fin) and internal morphology (e.g., stomach shape and size, gut length: GL) provide important information on a species' feeding ecology (e.g., Keast and Webb 1966, Schmitt and Holbrook 1984, Kaiser and Hughes 1993, Juanes 1994, Juanes and Conover 1994, Hart 1997, Wootton 1998. Exploration of the relations between various feeding-related morphological characteristics with body length ** , such as body girth (e.g., Stergiou and Karpouzi 2003), mouth dimensions (horizontal and vertical mouth opening, gape area; e.g., Karpouzi and Stergiou 2003), and GL (e.g., Karachle and Stergiou 2006, 2007), are of great importance for understanding the biology and ecology of fishes (e.g., Peters 1983, Kramer and Bryant 1995a, b, Wootton 1998, Froese and Pauly 2000, as well as pinpointing the ecological role of a species in the aquatic food webs (e.g., Stergiou 2003, Froese and Pauly 2008).Gut length, in particular, provides important information on species' feeding habits in almost all vertebrate classes, e.g., fishes (Kramer and Bryant 1995a); reptiles (O'Grady et al. 2005); birds (e.g., Ricklefs 1996); and mammals (e.g., Chivers and Hladik 1980). In fishes, it can also be used as a reference point for interspecific comparisons (e.g., Al-Hussaini 1947). In this work, information on intestinal indices and relations between GL and body length and weight were compiled from the available bibliography. This data was related to species' feeding habits, fractional trophic level values (TROPHs) and taxonomy, as provided in FishBase (Froese and Pauly 2008), in order to identify possible patterns and correlations of feeding habits and evolutionary traits with intestinal growth. Background. The examination of morphological features related to feeding in fish, as well as their relation with body length, are of increasing scientific interest. In the present study, information on intestine (gut) morphometrics that appear in the relevant literature has been compiled, analysed, and discussed. Materials and Methods. Search of gut-related bibliography was conducted, using online literature databases on fish feeding and ecomorphology. The resulted data was tabulated. Relationships between mean, minimum, and maximum relative gut length (RGL) and intestine length weight index (ILW, Zihler's index), as provided by the original author, with species' fractional trophic levels (TROPHs; extracted from FishBase) were explored. Finally, using the relations between gut length (GL) and body length (L) provided by the original authors, regressions were reconstructed and compared based on species' feeding habits and taxonomy.Results. The amount of information related to gut morphometrics referred to 498 species. The relations between GL and L referred to 71 species, but four species were omitted from the analyses. Mean, minimum, and maximum RLG and ILW values were negatively related (for all cases: P < 0.01) with TROPH. The GL-L regressions performed for 67 species revealed ...

Dieta de Hatcheria macraei (Girard, 1855) (Teleostei, Siluriformes, Trichomycteridae) en el rio Chubut, Argentina

“…Se encontró una relación significativa entre las longitudes intestinal y estándar siendo la ecuación que expresa dicha relación Li = 0,6081 Lst-6,9595, con un coeficiente de correlación de r = 0,917. Estos valores coinciden con lo observado para Trichomycterus corduvense (Ferriz, 1998) y permiten clasificar a esta especie dentro del grupo de los carnívoros (Karachle & Stergiou, 2010).…”

Morphometrics and Allometry in Fishes

“…Carnivores<omnivores<herbivores<detritus feeders (e.g., Kapoor et al 1975, Ribble & Smith 1983, Kramer & Bryant 1995b, Karachle & Stergiou 2010a. The same pattern is also true in other vertebrate classes (e.g., reptiles: O' Grady et al 2005, birds: Ricklefs 1996, and mammals: Chivers & Hladik 1980.…”

“…In recent years, attempts have been made to relate other morphological characteristics of fishes, such as mouth (e.g., Karpouzi & Stergiou 2003, Chalkia & Bobori 2006, Karachle & Stergiou 2011a, intestine (e.g., Kramer & Bryant 1995a, b, Karachle & Stergiou 2010) and tail (Karachle & Stergiou 2004), to TL, and as well as to feeding habits and fractional trophic Intestine (or gut) length (GL) is considered to be an indicator of diet (Kramer & Bryant 1995a) and, particularly in fishes, can be used for interspecific dietary comparisons (e.g., AlHussaini 1947, Karachle & Stergiou 2010a). For a given body length, intestine in herbivorous species is longer than in omnivorous ones, and in omnivorous species longer than in carnivorous ones (e.g., Kapoor et al 1975, Kramer & Bryant 1995b, Karachle & Stergiou 2010a.…”

“…For a given body length, intestine in herbivorous species is longer than in omnivorous ones, and in omnivorous species longer than in carnivorous ones (e.g., Kapoor et al 1975, Kramer & Bryant 1995b, Karachle & Stergiou 2010a. Hence, the widely accepted pattern of fish GL variation in relation to species feeding habits is:…”

Dieta de Pachyurus bonariensis (Steindachner, 1879) (Perciformes, Sciaenidae) en Mocoreta, río Uruguay, Argentina

“…La Li guarda una relación positiva con el incremento de LS (Li = 0,7559LS -3,4813). Estos resultados permiten clasificar esta especie dentro del grupo de los carnívoros (Karachle & Stergiou, 2010). De acuerdo al diagrama de estrategia alimentaria propuesto por Amundsen et al (1996), en ambos grupos, P. bonariensis es generalista (Fig.…”