Some animals span the world. Others live in an area the size of a pond.
The Texas blind salamander exists in one pool of an aquifer in a specific region of Texas. The salamander, which lives in San Marcos Pool in a cave in Hays County, Texas, grows to about five inches long all told. The predator-prey relationship of the cave means that the salamander eats a blind shrimp also only found in the pond and several smaller species of insects and mollusks.
Texas conservation biologists have tried to breed the salamander in case something happens at this small biome. Of course, people have decided to be total jerks about it, hundreds of them from a lab. Of course, the thief might have been a .
The Guadalupe fur seal can only be found in great numbers on one island in the world, Isla Guadalupe. The island is located about 124 miles off the coast of Mexico in the Pacific. A few colonies have moved elsewhere, but by-and-large, the 10,000 seals sit contently on the coast of the island's 94 square miles.
This tiny relative of the ocean-faring isopod once had a range of roughly three springs in New Mexico. Then it was nearly wiped out. According to , Sedillo Springs dried up in 1988 due to a spring flow obstruction, killing off the last wild isopods. A captive breeding program led to a new population of the isopods, which were placed in eight concrete tanks to more closely regulate the last outpost of the species.
The vaquito is a dolphin relative that's less than five feet long. It's confined to a narrow area in the northern part of the Gulf of California, where poaching and fisherman's nets have driven its meager population to the brink of extinction. There are around 30 left in the wild.
In the upper peninsula of Michigan and the southern tip of Ontario in spring and summer, you can find the Kirtland's warbler. You can't find it much of anywhere else. The bird requires dense areas of jack pine to make its habitat, something only found in the taiga region of North America.
After a population bottleneck in the 20th century that led it to extinction, the bird has since rebounded. Of course, climate change's effects on the taiga could change that, depending on the fortunes of the jack pine.
"Hold on," you say. "The Pinta Island tortoise is dead—snuffed out when Lonesome George took his last breath." You are mostly right. But there's a bizarre twist in the story: a few Pinta Island tortoises . Just not on Pinta Island.
Pinta is one of many islands in the Galapagos chain. The islands are most famous for influencing the works of Charles Darwin, as each island seemed to have unique variations on the same species. That meant that there were several subspecies of Galapagos tortoises around the island chain.
Here's where it gets a bit gruesome. Tortoises were often held on ships over long periods of time as a food source. They need relatively little food themselves, meaning that the giant tortoises could make a feast for sailors any time needed. As expeditions wound down, a few of those tortoises were thrown overboard, some near Isabella Island. Isabella Island has an area cut off from the rest of the land called Volcano Wolf. At some point a few Pinta Island tortoises found themselves washing up on these shores and breeding with their cousin subspecies there.
. They appeared to be relatively young and first generation hybrids, meaning that the Pinta Island tortoise can still (possibly) be found on Isabella Island.
Most marsupials live in Australia, constraining their range a bit already. But the quokka is only found in the southwest corner of Australia and a few nearby islands, giving it an even smaller area to live than its cousins.
Quokkas are fearless and curious of humans, which can lead to some unfortunate interactions with less-than-kind humans who come into with these puffy cheeked critters. Even some more altruistic people can mess up a quokkas life by feeding them. The quokka survives on vegetation not just for food, but for water.
Interestingly, the quokka has taken root in Two Peoples Bay Nature Reserve, a reserve initially set up to protect noisy scrub-birds. Since then, the Gilbert's potoroo has taken root. This species is possibly the most endangered marsupial in the world. Thus, one of the most vulnerable marsupials lives among one of the most endangered.
The Gilbert's potoroo, a small kangaroo-like marsupial (see the last entry) was once thought to be basically extinct. And indeed, it's perilously close to it, as fires wiped out half of the 100-some population in 2015. Right now, the species is mainly confined to the Two Peoples Bay Nature Reserve, though there are efforts to introduce it elsewhere.
According to the , the animal has never had a wide range, sticking close to that region of southwest Australia. This may have doomed the Gilbert's potoroo from the start — though there are numerous other species of potoroos throughout Australia.
The tuatara has remained only slight changed in the last 220 million years, and likely will survive with only light tweaks for the next 220 million. The primitive reptile can only be found on chains of islands off the coast of the North Island of New Zealand.
One species, the Brothers Island Tuatara, has only about 400 individuals on North Brother Island, but the island is small enough that this hasn't imperiled the lizard yet. Around 60,000 other individuals of the Northern Tuatara are scattered across 29 islands. After the eradication of rats, their numbers rebounded and are considered least concern by the IUCN. (The Brothers Island Tuatara is listed as vulnerable.)