I also have been thinking about giraffes a bit since visiting the new Hall of Mammals at the National Museum of Natural History last weekend.
In the time since I started volunteering at the National Zoo, it's had Masai, reticulated and, now, Rothschild's giraffes (Randall is now in quarantine, but can be partially seen in the Elephant House; another male will come later, probably after Malaika goes back to Disney's Animal Kingdom). This is one-third of the number of identified giraffe subspecies.
According to the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species (as of 1996), giraffes are classified as "LR:cd" (lower risk: conservation dependant). As a species, giraffes do not "satisfy the criteria for any of the categories Critically Endangered, Endangered or Vulnerable;" however, they are "the focus of a continuing taxon-specific or habitat-specific conservation programme targeted towards the taxon in question, the cessation of which would result in the taxon qualifying for one of the threatened categories above within a period of five years." Although giraffes are not endangered as a species, some subspecies are endangered. The Nigerian giraffe, for example, is now extinct in Nigeria and can only be found in Chad. Others, such as the Rothschild's giraffe, are threatened by hybridization with other subspecies as habitat destruction or well-meaning relocation efforts bring different subspecies into the same habitat.
The species name is Giraffa camelopardalis. The word giraffe comes from the Arabic الزرافة (zarāfa), which is purported to mean "tallest of all." Camelopardalis is the giraffe constellation and camelopard is the heraldic term for a giraffe. Both words come through Latin camelopardus from the Greek καμηλοπάρδαλη (kamelopardale), so called because giraffes appear to have the head of a camel and the spots of a leopard.
Thinking of their spots, while the evolutionary advantages of patterned fur are relatively easy to theorize about, exactly how the patterns develop is less clear. Since, with giraffes at least, the patterns at birth change only in size as the animal grows, something in utero lays down the pattern that will literally mark the individual giraffe for life long before the hairs themselves develop. Marcelo Walter's Ph.D. thesis talks about this a bit, even though his goal is realistic computer modeling of animal patterns. (The pertinent information is at the end of Chapter 2 "Models for Mammalian Coat Pattern Formation," which ends with a case study of pattern formation in giraffes.) In the thesis, Walter suggests that giraffe patterns are laid down around day 36 of development; giraffe gestation lasts about 457 days.
The nine subspecies and descriptions (drawn from Giraffe Lover) are:
- Reticulated giraffe or Somali giraffe (G.c. reticulata) -- large, polygonal liver-colored spots outlined by a network of bright white lines. The blocks may sometimes appear deep red and may also cover the legs. Range: northeastern Kenya, Ethiopia, Somalia.
- Angolan giraffe or Smoky giraffe (G.c. angolensis) -- large spots and some notches around the edges, extending down the entire lower leg. Range: Angola, Zambia.
- Kordofan giraffe (G.c. antiquorum) -- smaller, more irregular spots that do cover the inner legs. Range: western and southwestern Sudan.
- Masai giraffe or Kilimanjaro giraffe (G.c. tippelskirchi) -- jagged-edged, vine-leaf shaped spots of dark chocolate on a yellowish background. Range: central and southern Kenya, Tanzania.
- Nubian giraffe (G.c. camelopardalis) -- large, four-sided spots of chestnut brown on an off-white background and no spots on inner sides of the legs or below the hocks. Range: eastern Sudan, northeast Congo.
- Rothschild's giraffe or Baringo giraffe or Ugandan giraffe (G.c. rothschildi) -- deep brown, blotched or rectangular spots with poorly defined cream lines. Hocks may be spotted. Range: Uganda, north-central Kenya.
- South African giraffe (G.c. giraffa) -- rounded or blotched spots, some with star-like extensions on a light tan background, running down to the hooves. Range: South Africa, Namibia, Botswana, Zimbabwe, Mozambique.
- Thornicroft giraffe or Rhodesian giraffe (G.c. thornicrofti) -- star-shaped or leafy spots extend to the lower leg. Range: eastern Zambia.
- West African giraffe or Nigerian giraffe (G.c. peralta) -- numerous pale, yellowish red spots. Range: Chad.
- Cape giraffe (G.c. capensis)
- Lado giraffe (G.c. cottoni)
- Congo giraffe (G.c. congoensis)
- Transvaal giraffe (G.c. wardi)
- Giraffes Giraffes
- Oakland Zoo giraffe fact sheet
- Victoria's Open Range Zoo giraffe fact sheet (PDF)
- National Zoo giraffe fact sheet
- Cheyenne Mountain Zoo giraffe information
- Columbus Zoo & Aquarium giraffe page
- AZA Antelope Taxon Advisory Group giraffe fact sheet
- Adopt a giraffe at the National Zoo
I don't know how much I'll get to blog during the holiday madness of the next few days, so Merry Christmas to all who mark that holiday, Happy the rest of חֲנוּכָּה for those who mark that holiday, and have a great couple of days to everyone else who doesn't have a holiday or celebration going on these next few days.