“to make something sacred by dedicating it to the gods“
“to kill (an animal, plant, or any other living creature) as part of a scientific experiment”

...or, perhaps, to do both at once?

The sacrifice of both human women and bunny rabbits seems to stem directly from the ongoing crusade to beat the death-in-third-trimester infertility problem.

By contrast, the sacrifices involved at the Hydra station have a different flavor to them, a military flavor. On the smaller LOST island we saw an intriguing derelict laboratory remaining from its DHARMA Initiative days, the Hydra station. The name itself has flavor, referring to a deadly multi-headed mythological beast (more on that following below, with links to illustratons).

The corridors at the Hydra station open to the ocean such that they can be flooded (and in the past, if done correctly as designed, with a high degree of precision I would think), presumably allowing a massive veterinary operating stage (located in the room in which Jack was locked up) to be just below the surface of the water. This means a heavy animal such as a dolphin (like Flipper) or polar bears (polar bears are quite at home in water) could be tranquilized and then easily floated down corridors and onto the operating stage while cradled in a cargo net by a human team.

There is precedent for using dolphins as military operatives. Though the history of such research has been denied, evidence suggests the U.S. military and CIA have experimented with using dolphins to plant magnetic bombs on ships and for other military ends (www.harmlesslion.com/dolphin...ent.htm) and also performed highly hazardous biological weapons research on a Pacific atoll (an atoll which was subsequently incinerated by an H-bomb blast: a microbiologist I knew long ago when I was a youth had personally worked on that project and related this history to me).

Polar bears were also maintained at the Hydra station in Skinnerian behavior-modification cages which seem to test their intelligence. Polar bears are very smart; indeed they are the only arctic predator which will stalk and kill humans. They hide their black noses with white paws to blend in with the snow and avoid being detected until it is too late, as while waiting alongside holes in arctic ice used by seals for breathing. It appears at least two of the clever polar bear subjects of whatever Frankensteinian research was going on at the Hydra station escaped, one Creature slipping off the leash and through both time and space to end up in a Tunisian desert of the distant past. The other Creature to have escaped (the evidence suggests at least one pregnant sow made it to the larger LOST island) and/or its descendants hectored the LOSTies soon after their arrival on the island.

If the DHARMA Initiative was sacrificing animals at the Hydra station as part of the research conducted there, then this research would seem to be targeted toward producing powerful, ruthless, cunningly intelligent animal weapons capable of operating in marine and arctic environments. Why animals and not conventional military weapons? Conventional weapons are usually made of metal ...and machines such as compasses seem to perform differently than intended when subjected to the strange electromagnetic effects of the island.

If the sacrifices of animals such as polar bears at the Hydra station were to produce, literally, a Hydra force, then who or what was this Hydra force being readied to attack or defend?

Hydra: “it had fatally poisonous breath and when one head was severed, grew two in its place; its central head was immortal. Hercules, sent to kill the serpent as the second of his 12 labors, succeeded in slaying it by burning off the eight mortal heads and burying the ninth, immortal head under a huge rock. The term hydra is commonly applied to any complex situation or problem that continually poses compounded difficulties”
encarta.msn.com/encycloped...ology).html

“The Hydra which lived in the swamps near to the ancient city of Lerna in Argolis, was a terrifying monster which like the Nemean lion was the offspring of Echidna (half maiden - half serpent), and Typhon (had 100 heads), other versions think that the Hydra was the offspring of Styx and the Titan Pallas. The Hydra had the body of a serpent and many heads (the number of heads deviates from five up to one hundred there are many versions but generally nine is accepted as standard), of which one could never be harmed by any weapon, and if any of the other heads were severed another would grow in its place (in some versions two would grow). Also the stench from the Hydra's breath was enough to kill man or beast (in other versions it was a deadly venom). When it emerged from the swamp it would attack herds of cattle and local villagers, devouring them with its numerous heads. It totally terrorized the vicinity for many years.”
theochem.chem.rug.nl/resourc...ica.html

Illustrated Hydra goodness:
en.wikipedia.org/wiki/Lernaean_Hydra
www.eaudrey.com/myth/hydra.htm

BTW, how exactly did Dr. Charlotte Staples Lewis know there would be a collar with a Hydra station emblem on the ancient remains of a polar bear unearthed in an archaeological dig site in the Tunisian desert? She went directly to the bones, knew them for polar bear remains, and reached for the collar as if she expected it to be there. The expression on her face upon seeing the Hydra emblem was one of triumph.

Hmmm. Maybe that polar bear did not escape. Maybe part of its sacrifice was to be deliberately sent through the past into the desert. So, how would she know to expect its remains there, though, unless she perhaps was in on it’s sending in the first place?

Indeed, the term "hydra" being "commonly applied to any complex situation or problem that continually poses compounded difficulties" suggests that somebody or somebodies (Jacob vs Abaddon?) is/are attempting to alter timeflows to produce different outcomes, and more than willing to sacrifice animals and people to do so. Alas, each move which is made compounds the complexity of the interwoven skein, hydra-like, perhaps beyond anyone's control.