Cryptomys mechowi

About: Cryptomys mechowi is a research topic. Over the lifetime, 11 publications have been published within this topic receiving 380 citations.

Unusual cone and rod properties in subterranean African mole‐rats (Rodentia, Bathyergidae)

Abstract: We have determined the presence of spectral cone types, and the population densities of cones and rods, in subterranean mole-rats of the rodent family Bathyergidae, for which light and vision seems of little importance. Most mammals have two spectral cone types, a majority of middle- to long-wave-sensitive (L-) cones, and a minority of short-wave-sensitive (S-)cones. We were interested to see whether the subterranean bathyergids show the same pattern. In three species, Ansell's mole-rat Cryptomys anselli, the giant mole-rat Cryptomys mechowi and the naked mole-rat Heterocephalus glaber, spectral cone types and rods were assessed immunocytochemically with opsin-specific antibodies. All three species had rod-dominated retinae but possessed significant cone populations. A quantitative assessment in C. anselli and C. mechowi revealed surprisingly low photoreceptor densities of 100 000-150 000/mm(2), and high cone proportions, approximately 10% (8000-15 000/mm(2)). In all three species, the vast majority of the cones were strongly S-opsin-immunoreactive; L-opsin immunoreactivity was much fainter. In C. anselli, approximately 20% of the cones showed exclusive S-opsin label, approximately 10% exclusive L-opsin label and approximately 70% strong S-opsin and faint L-opsin double label (potential dual-pigment cones). This is the first observation in any mammal of an S-opsin dominance and low levels of L-opsin across the entire retina. It contrasts starkly with the situation in the muroid blind mole-rat Spalax ehrenbergi, which has been reported to possess L-opsin but no S-opsin. Evidently, within rodents an adaptation to subterranean life is compatible with very different spectral cone properties.

Evolution of eusociality in the Bathyergidae. The case of the giant mole rats (Cryptomys mechowi).

Abstract: Eguchi, E.: J. Exp. Biol. 123, 1 (1986) 11. Hariyama, T., Tsukahara, Y.: Comp. Biochem. Physiol. 91A, 529 (1988) 12. Hariyama, T., Tsukahara, Y.: J. Exp. Biol. (in press) 13. Cronin, T. W., Marshall, N. J.: J. • Comp. Physiol. A 166, 261 (1989) 14. Cronin, T. W.: ibid. 164, 737 (1989) 15. Smith, K. C., Macagno, E. R.: ibid. 166, 597 (1990) 16. Frisch, K. yon: Zool. Jb. 35, 1 (1914) 17. Crescitelli, E: J. Comp. Physiol. A 157, 323 (1985) 18. Peitsch, D., et. al. : ibid. 170, 23 (1992) 19. Meyer-Rochow, V. B.: ibid. 139, 261 (1980)

Thermoregulation in three species of Afrotropical subterranean mole-rats (Rodentia: Bathyergidae) from Zambia and Angola and scaling within the genus Cryptomys

Abstract: The thermoregulatory characteristics of three species of Cryptomys from Zambia and Angola are examined and, together with published data on four other species of Cryptomys from southern Africa, used to determine whether scaling occurs in this genus of subterranean rodents. The thermoregulatory properties of acclimated giant Zambian mole-rats, Cryptomys mechowi ( $$\bar x$$ =267 g), Angolan mole-rats, Cryptomys bocagei ( $$\bar x$$ =94 g) and Zambian common mole-rats Cryptomys hottentotus amatus ( $$\bar x$$ =77 g) are as follows. Mean resting metabolic rates (RMRs) within the respective thermoneutral zones were 0.60±0.08 cm3 O2 g-1 h-1 (n=12) for C. mechowi; 0.74±0.06 cm3 O2 g-1 h-1 (n=8) for C. bocagei and 0.63±0.06 cm3O2 g-1 h-1 (n=21) for C. h. amatus. The thermoneutral zones (TNZs) of all three species are narrow: 29–30°C for C. mechowi; 31.5–32.5°C for C. bocagei and 28–32° C for C. h. amatus. The increase in mean RMR at the lowest temperatures tested (15° C for C. mechowi, 18° C for C. bocagei and C. h. amatus) was 2.35, 2.2 and 3.82 times their RMR in the TNZ respectively. Body temperatures are low, 34±0.53° C (n=24) for C. mechowi, 33.7±0.32° C (n=20) for C. bocagei and 33.8±0.43° C (n=40) for C. h amatus. At the lower limit of thermoneutrality, conductances are 0.09±0.01 cm3 O2 g-1 h-1 °C-1 (n=30) in C. mechowi; 0.12±0.01 cm3 O2 g-1 h-1 °C-1 (n=20) in C. bocagei and 0.12±0.03 cm3 O2 g-1 h-1 °C-1 (n=32) in C. h. amatus. The range in mean body mass among the seven species of Cryptomys examined for scaling was 60 g (C. darlingi) to 267 g (C. mechowi). There is no clear relationship between RMR within the TNZ and body mass. The resultant relationship is represented by the power curve RMR=2.45 mass-0.259.

Natural history of the giant mole-rat,cryptomys mechowi (rodentia: bathyergidae), from zambia

Abstract: We present the 1st detailed field study on the giant mole-rat (Cryptomys mechowi), a eusocial subterranean bathyergid rodent from mesic areas of subequatorial central Africa. In Copperbelt Province, Zambia, we found giant mole-rats in a variety of habitats including agricultural fields, bushland, marshes, and forests. Soil types varied in hardness and air content, and varied vertically and horizontally. Burrow systems of single colonies were 0.2–2.5 ha. The diameter of burrows was about 8 cm, and the maximum depth was about 200 cm. Nests were found at an average depth of 91 cm (n = 8). Further characteristics of nests, food and defecation chambers, diet, helminth parasites, and commensals are described. Colony size ranged from 3 to >20 with a sex ratio of 1:1.2 (n = 65) in favor of females, with 8% juveniles, 39% subadults, and 53% adults. A significant sexual dimorphism was found in the body mass (345 g ± 95 SD in males versus 252 ± 34 g in females). A defined breeding season was not apparent. B...

The colony structure and social organization of the giant Zambian mole-rat, Cryptomys mechowi

Abstract: Cryptomys mechowi is a social subterranean mole-rat which inhabits the mesic regions of south-eastern and central Africa. Giant mole-rats live in colonies of up to 11 animals in which reproduction is normally restricted to the largest male and female in the colony. In this preliminary study on a laboratory-reared colony, the non-reproductive members of the colony could not be placed into clearly defined, work-related groups based on body mass. The colony showed a work frequency related division of labour. Reproductive animals performed little work, 3-4% of the total work. The non-reproductive caste was divided into two groups based on the amount of burrow maintenance activity: those performing between 7-11% of total work and those ranging from 15-22% of total work. Male members of the colony tended to perform more work than the females. The dominance hierarchy of the colony was found to be nearly linear, with a value of 0.83 calculated from Landau's linearity index. The reproductive animals were the most dominant in their respective gender. Dominance was not age-related. However, non-reproductive males tended to be more dominant than non-reproductive females. Social organization within the giant Zambian mole-rat is compared with other southern African Cryptomys species in the light of the eusociality continuum.