Brent Huffman (c), http://www.ultimateungulate.com/Hyracoidea/Procavia_capensis.html
Basic Biology
Pallas identified P.capensis in 1766 (Huffman 2004). Hyraxes, or species from the order Hyracoidea, Family Procaviidae are the smallest herbivorous hoofed mammals, similar to rodents' body form, but related to Proboscidea (elephants) and Sirenia (dugongs and manatees) with which they share numerous physiological similarities (Bigalke 1968, Estes 1991).
Hyraxes themselves have a number of similarities - in Heterohyrax, the 2n is 54, identical to Procavia and Dendrohyrax, and sequences of 2 mtDNA genes show close relation between Procavia and Heterohyrax (Barry, Shoshani 2000). Even though there are some conspecific characteristics, it all applies, therefore below is provided information on several species of hyraxes.
Body Description (Huffman 2004)
Coloration of P. capensis is grizzled gray-brown, varying by population.
Flanks are lighter, underpants are whitish. Ears are small and circular, the
pointed head has black whiskers up to 18 cm. In hot arid habitats the hair is
short, but in alpine populations it is thick and soft (Hoeck).
Brent Huffman (c), http://www.ultimateungulate.com/Hyracoidea/Procavia_capensis.html
Body Size
Average size of adult P.capensis is variable across the continent,
closely linked to average annual precipitation (Hoeck). Male hyraxes are slightly
larger (4 kg, 3.6 kg for females), tail length is 11-24 mm, ear is 27-38 mm,
hindfoot is 65-76 mm (Jansa 1999). Rock hyraxes body length is 44-54 cm, height
at shoulder is 15-25 cm, the tail is virtually nonexistent, weight 1.8-2.5 kg
(Huffman 2004).
H. brucei is cited to be 43 cm of length and 1.8 kg of weight as adult
on average (49 cm and 3.1 kg for P.johnstoni) (Caro, Alawi 1985).
Hyraxes increase in weight as follows: 1 1/2 month - 0.4 kg (Heterohyrax) and
0.6 (Procavia), 3 month - 0.6 (H.) and 0.9 (P), 6 month - 0.8 (H), 1.6 kg (P),
1 yr. - 1.1 (H), 2.7 kg (P). Full weight is attained at about 3 years (Caro,
Alawi 1985).
According to Gompper et al. (1997) the age of first reproduction was 2.7 years
for the females.
Feet
The fore feet are plantigrade, the hind feet are semi-digitigrade, with
fore feet having 3 toes, and rear ones having 4 (Jansa 1999, Huffman 2004).The
feet have short, flat, hooflike nails, but the second digit that has a curved
claw used for grooming. Skin glands provide traction for the rubbery thick soles
during climbing and running, but they are not suitable for digging (Barry, Shoshani
2000; Hoeck). They crouch with all feet on the ground, back hunched, moving
in a creeping walk, maximum speed is about 5 m/s(Barry, Shoshani 2000).
Teeth
A single pair of tusklike upper incisors, and same dental formula (i 1/2, c
0/0, p 4/4, m 3/3, total 34) exist for Heterohyrax, Dendrohyrax, and northern
subspecies of P.capensis (Barry, Shoshani 2000).
Images courtesy of Mammal Division (copyright holder), Museum
of Zoology, University of Michigan. http://animaldiversity.ummz.umich.edu/site/resources/skulls/procavia/p._capensis/162721.um.jpg
and http://animaldiversity.ummz.umich.edu/site/resources/skulls/procavia/p._capensis/162720.lateral.jpg
Glands (Barry, Shoshani 2000)
The dorsal gland in sexually mature adults is composed of lobules of glandular
tissue with 25-40 alveoli. It lies under a patch of erectile hair and functions
in mating and mother-offspring recognition. Other glands are found above the
eyes, under the chin, and in the preputial and circumanal regions.
Senses (Barry, Shoshani 2000)
The ability to stare into the sun is due to a pupil protective umbraculum, so
that predator detection can be accomplished even during staring at the sun.
Tactile hairs are found on the head and the body, providing information during
underground movement, when eyes can not function as well. Jacobsen's organ serves
as a specialized olfactory structure.
Thermoregulation and excretion (Barry, Shoshani 2000)
Huddling and stacking together for warmth take up to 95% of day. The yellow-spotted
hyrax (along with other hyraxes) is found to have low weight-specific metabolic
rate, thermal ability, and therefore is highly dependent on behavioral thermoregulation.
Crowding, basking, and hiding in shade are some methods for that (Huffman 2004).
Observations show that in heavy rain, hyraxes become inactive (Caro, Alawi 1985).
Body temperature is normally between 35 to 37C, but fluctuated up to 7C when
air temperatures change. Evaporative water loss by dripping from nostrils and
soles increases above 25C. Oxygen consumption increases at temperatures below
22C. Mean metabolism at 25-30C is 0.52 ml O2 g^-1 h^-1. Also, low urine and
fecal volume help retain water, which is solely provided by vegetation. The
communal latrines which are close to the sleeping quarters are covered with
a white crystalline residue of calcium carbonate, called hyraceum and used as
medicine (Barry, Shoshani 2000).
Lineage retention
Even though the study by Gompper et al.'s (1997) dealt with the bison, the acorn
woodpecker, and the white-nosed coatie, they used other data for comparison.
According to Hoeck, the Heterohyrax brucei, studied for a period of 6
years, retained 46% of its lineage. From the presented table it is seen that
there is a definite trait for bigger animals to retain more lineage information,
compared to smaller animals which loose it faster. The authors conclude that
smaller species of mammals (rodents and hyrax) loose between 8-24% of lineage
per generation, compared to larger carnivores, primates, and ungulates, which
loose only 0.4-11% per generation.
Life Span
Hyraxes life span has been recorded to be up to more than 10 years (Caro, Alawi
1985).