The Topography and Gross Anatomy of the Gastrointestinal Tract of the Cape Dune Mole‐rat (Bathyergus suillus)

Abstract

The Cape dune mole-rat, Bathyergus suillus, is the largest truly subterranean rodent in the world and is restricted to sandy soil areas of the southern and South-western Cape Province. These animals are herbivorous, feeding mostly on the below ground portions of grass and geophytes. The present study was undertaken to explore whether there are any gross anatomical gastrointestinal adaptations associated with the herbivorous diet of the Cape dune mole-rat and to provide a basis for further investigations into the nutrition and ecology of this animal. The stomach was unilocular (simple) and the entire internal aspect displayed macroscopically visible glandular epithelium. The caecum was voluminous and arranged into a spiral of approximately one and a half turns. The tip of the caecum resembled a vermiform appendix and lay against the left lateral abdominal wall. The ascending colon consisted of proximal and distal portions, arranged in a large double loop and attached to each other by a fat-filled mesenteric fold. The looped, folded ascending colon filled the right side of the abdominal cavity, lying against the right dorsal, lateral and ventral abdominal wall. The internal structure of the ascending colon revealed a shallow groove, lined on either side by a row of papillae. The simple, glandular stomach in conjunction with a prominent caecum and a greatly enlarged ascending colon suggests that this animal is a hindgut fermenting herbivore, rather than a caecal fermenter, as is the case in most rodent species.

Anatomy of the Gross Intestine of the Capybara <i>(Hydrochoerus Hydrochaeris)</i>

“…In the capybara, we recognized the same parts. The fact that the cecum was voluminous agrees with the general trend in rodents (Perrin and Curtis, 1980;Kotze et al, 2006).…”

“…Previous studies show demonstrate that species belonging to the order Rodentia have great differences in their intestinal anatomy (Bonfert, 1928;Snipes, 1979a;1979b;1981, 1982a, 1982bPerrin and Curtis, 1980;Snipes et al, 1988;1990;Nieters et al, 2003;Kotze et al, 2006;Pérez et al, 2008;2009;2011). Especially the cecum and ascending colon shows large differences among rodent species.…”

The colonic groove or furrow: A comparative morphological study of six species of African mole‐rats (Rodentia, Bathyergidae)

“…Trapping of bacteria in mucous in the colonic groove and allowing it to move back into the cecum effec- tively prevents the washing out of bacteria, thereby increasing their retention time in the digesta (Cork et al, 1999). Although the groove has been previously observed in mole-rats (Gorgas, 1967;Kotzé et al, 2006), its prevalence in the bathyergid family of African mole-rats and its potential role in digestion and in the CMS have not been investigated to date.…”

“…In a study of the anatomy and topography of the intestinal tract of the Cape dune mole-rat, B. suillus, Kotzé et al (2006) describe a longitudinal colonic groove lined on either side by a row of papillae. Gorgas (1967) and Perrin and Curtis (1980) have observed the presence of a groove in various mole-rat species.…”

Seasonal effects on digging activity and burrow architecture in the Cape dune mole-rat,Bathyergus suillus(Rodentia: Bathyergidae)

“…The Cape dune mole-rat (Bathyergus suillus) is the largest truly subterranean rodent (up to 2.5 kg) (Jarvis & Bennett 1991;Kotze et al 2006), with males being significantly larger (Davies & Jarvis 1986;Kinahan et al 2007). Bathyergus suillus is limited in its distribution to the sandy loams of the southern and western Cape Provinces, South Africa, possibly due to the high energetic costs of excavation using its enlarged mole-like forepaws (Bennett & Faulkes 2000).…”