An ultrastructural focus on the buccal cavity of the grey gurnard Eutrigla gurnardus (Linnaeus, 1758): Adaptative dietary implications

Abstract

The current investigation represented the first anatomical description of the buccal cavity of the grey gurnard Eutrigla gurnardus. For the achievement of this study, 10 heads of mature fish were used for SEM examinations. The morphological characteristic appearance of the buccal cavity has shown several adaptations in relation concerning its feeding habits. The median fissure of the upper lip divided the upper lip into two halves, this fissure appeared to be formed from many micro‐tubercles with numerous taste buds which aid in holding mucus secretion to the cell surface, help in mucus spread, and provide mechanical protection to the epithelium. Velum had two regions: median and peripheral region. The epithelium covering of the median region of the upper velum had dots‐like epithelial protrusion that carrying numerous taste buds, meanwhile, the epithelium covering of the lower velum not carried taste buds but instead carried numerous small scales‐like structures. The palate is divided into two semicircular regions by small region of microridges into the anterior and posterior region. The slightly bifid tongue had a median tubercle with numerous small taste buds on its dorsal surface. Concluded, these data were necessary to understand the adaptation of fish to its habitat and in developing a new and better method for fishing of this type of fish.

Ultrastructural comparison between the oral cavity floor of the juvenile and adult Epinephelus aeneus: New vision of aging development and its carnivorous adaptation

“…The obtained results on the oral cavity floor of the juvenile and adult age-stages of the white grouper (E. aeneus) had a common feature that joined the two age-stages and enumerated numerous difference points between the two different age-stages (juvenile and adult) of the white grouper (E. aeneus). The obtained results on the oral cavity floor of the juvenile and adult age-stages of the white grouper (E. aeneus) confirmed the carnivorous behavior of the bottom feeder fish that present in the tropical and subtropical water area (Abumandour et al, 2021;Heemstra & Randall, 1993).…”

“…lower ridges was reported byYashpal, Kumari, Mittal, and Mittal (2006) in R. rita,Abumandour et al (2021) in carnivorous gray gurnard E. gurnardus, and Gamal et al (2012) in Clarias gariepinus. The current anatomical description observed that the longitudinal part of the lower incisive ridge not reached to the posterior border of the lower velum.The current observation of the lower lip of the white grouper E. aeneus in the juvenile and adult age-stages observed that the lip was hard in texture due to the presence of the numerous small lobulations with numerous microtubercles and microspines and the lip divided according to its position into a median single anterior part and two lateral part.…”

“…The current observation of the white grouper E. aeneus observed that the median lingual ridge was absent in 5 cm age fish, while the 18 cm fish age stages carried a median lingual ridge with numerous microtubercles and microlines on it. Also, the tongue had a median tubercle as described by Abumandour et al (2021) in grey gurnard E. gurnardus. Functionally, the presence of the median lingual tubercle or ridge on the dorsal lingual surface had a role in the raise the level of taste buds on the tongue above the level of the epithelium as reported in carnivorous R. rita (Yashpal, Kumari, Mittal, & Mittal, 2006), in Gilthead seabream (Levanti et al, 2017), and C. gariepinus (Gamal et al, 2012).…”

“…The current anatomical description of the white grouper E. aeneus in the different two age‐stages (juvenile and adult) observed that the oral cavity floor had a system of microridges of different names; microlines on the dorsal lingual surface (two lateral spinated lingual lines), microtubercles on the dorsal lingual surface (the median lingual tubercle), but the microridges appeared on the dorsal lingual surface, between the lip and the teeth (the median lingual ridge), the lower incisive ridge, the lower molar ridge, the median sublingual ridge, and the numerous ridges on the oral floor surface of the velum and lips in the adult (18 cm) fish. On the same line, the microfolds, the microridges, the ridges, the microvilli, and the cytoplasmic folds were reported in the herbivorous Oreochromis niloticus (Elsheikh, Nasr, & Gamal, 2012) and the observations of the microridges in the lower jaws in a carnivorous fish (Yashpal, Kumari, Mittal, & Mittal, 2006; Yashpal, Kumari, Mittal, & Mittal, 2009) in the catfish Rita rita and in the carnivorous grey gurnard Eutrigla gurnardus (Abumandour et al, 2021). Moreover, El‐Bakary (2011) observed the presence of the microridges that are arranged in different forms to give intricate patterns in juvenile and adult Sea Bass ( Dicentrachus labrax ).…”

“…The main role of the oral cavity floor was correlated with the processing of food including the food particles intake, the food processing, and the swallowing, in addition to different surrounding environmental conditions (Abbate et al, 2006; Abumandour et al, 2021; El Bakary, 2014; El‐Gendy, Alsafy, & Tanekhy, 2016; Fishelson, Baldwin, & Hastings, 2012; Gamal, Elsheikh, & Nasr, 2012; Nandi & Saikia, 2021; Yashpal, Kumari, Mittal, & Mittal, 2006; Yashpal, Kumari, Mittal, & Mittal, 2009). The current examinations of the oral cavity floor of the juvenile and adult white grouper ( E. aeneus ) agree with that reported in all fish species that the oral cavity of a carnivorous fish species with its related structures such as a different teeth bands, lips, and tongue played an important role in the prey capturing and the food particles transporting and helping in the adaptation to its surrounding environmental conditions in the different aquatic condition (Abbate et al, 2006; Abumandour et al, 2021; Alsafy et al, 2018; El‐Gendy et al, 2016; Fishelson, Baldwin, & Hastings, 2012).…”