Giraffe

[Update: lost, by Blogger, then recovered.]

Giraffa camelopardalis

(Public domain)

Kingdom: Animalia (critters, and such)

Phylum: Chordata (with a nerve chord)

Class: Mammalia (nursing must be awkward for these guys!)

Order: Artiodactyla (even-toed ungulates. Is it just me, or is there something Biblical about classifying animals by counting toes and whether they chew cud?)

Family: Giraffidae (giraffes and okapis)

Genus: Giraffa

Species: camelopardalis



The ancient Greeks named it the camel-leopard. Their preposterous size and proportions force an uncanny grace into their every movement. They are truly gorgeous animals.

The giraffe is tallest of all land-borne animals, reaching up to eighteen feet or so. Its closest relative is the Okapi, which just goes to show what an outlier this animal is.

It gets its own family, Giraffa. By bad luck, there is almost no fossil evidence of their history. I suspect that somewhere, someone is working out the giraffe genome to shed some light on this.

The adaptations to such height are equally extreme. The giraffe lives with a huge heart and very high blood pressure to get that stuff up into its head. Near the head is a network of shunts and bypasses that keep it from fainting or strokes when it bends down to take a drink. The vascularization of its legs is especially adapted to keep blood from pooling there.

And the lungs are oversized, and its breathing slowed, to make up for all that dead air in that long, long, trachea.

A post that I can't find right now [insert revision here] talked about the giraffe as an example of the differences between the Lamarckian and Darwinian ideas of origins. The schooldays stereotype is that Lemarck believed in inheritance of acquired characteristics: the stretching out of their necks to reach higher leaves led to longer necks. Under the supposed Darwinian view, giraffes that happened to have longer necks survived better, and passed that characteristic to their offspring.

In fact, neither had much to say about giraffes. Darwin knew nothing of genes and Mendelevian inheritance, and probably considered Lemarckian inheritance of acquired characteristics plausible. Add to that the fact that female giraffes are about two feet shorter than the males. So by the typical view females giraffes should have died out millions of years ago.

It's really more complicated than that. Evo-devo biology is teaching us just how complex it is; that small regulatory changes lead to huge morphological differences.

Giraffes also come up as models in speculations about the usual posture of the big, long-necked dinosaur sauropods.

Credit

This stuff is fun.

And I love giraffes.


Links:
Okapi
Giraffe at Wikipedia
Evo-devo at Wikipedia


Update: I mistook ungulate for ruminant. My bad, but only a scientist or farmer could really blame me.