Animals That Start With I: Ibex, Iguana, Impala and More

Iberian lynx

The Iberian lynx of Spain and Portugal was the world’s most threatened cat at the start of this century, with only 94 animals left in 2002. Breeding in captivity, reintroductions and work to restore rabbit numbers, its main prey, raised the count to 2,401 in 2024, and in 2024 the IUCN moved it from Endangered to Vulnerable. Read more about where lynx live in Europe.

Ibex

Ibexes are wild mountain goats famous for climbing near-vertical rock faces. The Alpine ibex lives in the Alps, where males weigh 67–117 kg (148–258 lb) and carry ridged, backward-curving horns 69–98 cm (27–39 in) long, while females have much shorter horns. The Nubian ibex of the deserts of northeastern Africa and Arabia is listed as Vulnerable.

Ibis

Ibises are wading birds with long, down-curved bills for probing mud. The scarlet ibis of northern South America gets its vivid color from pigments in the shrimp and crabs it eats. The sacred ibis was linked to the god Thoth in ancient Egypt, where huge numbers were mummified as offerings, and the northern bald ibis of Morocco and the Middle East is Endangered.

Icefish

Icefish, or crocodile icefish, live in the icy waters of the Southern Ocean around Antarctica. They are one of the very few groups of vertebrates that lack hemoglobin as adults, so their blood is almost clear. In 2021, scientists found a breeding colony of icefish on the floor of the Weddell Sea with an estimated 60 million nests.

Ichneumon wasp

Ichneumon wasps are a huge family of parasitic wasps, with about 25,000 described species, more than all the world’s birds and mammals combined. Most lay their eggs on or inside the larvae of other insects, which the wasp grubs then eat from within. Some females have an egg-laying tube longer than their body for reaching grubs hidden deep inside wood.

Iguana

The green iguana of Central and South America is a large, mostly plant-eating lizard that can reach about 1.5 m (5 ft) including its long tail. It has a light-sensitive “third eye” on top of its head that helps it detect the shadows of birds of prey. Green iguanas are invasive in South Florida; learn more in our green iguana profile.

Iiwi

The iiwi (ʻiʻiwi in Hawaiian) is a bright scarlet honeycreeper with a long, curved, salmon-colored bill that it uses to sip nectar from native Hawaiian flowers. Its feathers were once used in the cloaks and helmets of Hawaiian chiefs. Avian malaria, spread by introduced mosquitoes, has pushed it out of lowland forests, and it is listed as Vulnerable.

Immortal jellyfish

The immortal jellyfish (Turritopsis dohrnii) is a tiny jellyfish, only a few millimeters across, found in temperate and tropical seas. When stressed or injured, an adult can turn back into an immature polyp and start its life cycle again, something almost no other animal can do. It is not truly immortal, though: most are eaten or die of disease.

Impala

The impala is a graceful, reddish-brown antelope of the savannas and woodlands of eastern and southern Africa. When chased, it can leap up to 3 m (10 ft) high and cover up to 10 m (33 ft) in a single bound. Only males grow the slender, lyre-shaped horns, which are 45–92 cm (18–36 in) long.

Imperial eagle

Two large eagles carry this name, and both are listed as Vulnerable. The Spanish imperial eagle lives almost only in Spain and Portugal; by the 1960s just 30 pairs remained, but protection, including making power lines safer, helped it recover to over 300 pairs by 2011. The eastern imperial eagle breeds from southeastern Europe to Central Asia.

Inchworm

Inchworms are the caterpillars of geometer moths, a family of around 23,000 species. Because they have legs only at the front and back of the body, they move by drawing the rear end up to the front in a loop, then stretching forward again. The family name means “earth measurer”, because they seem to measure the ground as they go.

Indian peafowl

The Indian peafowl is native to India and Sri Lanka, and the male, the peacock, is India’s national bird. The famous fan of shimmering feathers is not the tail itself but a train of greatly lengthened feathers that cover it, each tipped with an eyespot. The plainer female is called a peahen.

Indian rhinoceros

Also called the greater one-horned rhinoceros, this armored-looking giant lives in grasslands of northeastern India and Nepal, with the largest population in Kaziranga National Park. Bulls average about 2,070–2,200 kg (4,560–4,850 lb). Numbers have risen from fewer than 200 in the early 20th century to about 4,075 in 2025, and it is listed as Vulnerable.

Indigo bunting

The male indigo bunting is a brilliant blue songbird of eastern North America in summer, but it has no blue pigment: its feathers are actually dark, and the color comes from the way their structure scatters light. Indigo buntings migrate at night, and planetarium experiments in the 1960s showed that young birds learn to steer by the stars.

Indri

The indri is one of the two largest living lemurs, weighing 6–9.5 kg (13–21 lb), and lives only in the rainforests of eastern Madagascar. Family groups sing eerie, wailing songs that can last from under a minute to more than three minutes. Unlike other lemurs, it has only a stubby tail. It is Critically Endangered, mainly because of forest loss and hunting.

Inland taipan

The inland taipan of the dry plains of central eastern Australia has the most toxic venom of any snake, based on tests in mice. It is shy and lives in remote country, so bites are very rare; anyone bitten by a snake should seek emergency medical help immediately. Its scales darken in winter, which helps it absorb more heat from the sun.

Irrawaddy dolphin

The Irrawaddy dolphin has a rounded head with no beak and lives in coastal waters and large rivers of South and Southeast Asia, including the Ayeyarwady (Irrawaddy), Mekong and Mahakam. It also lives in lagoons such as Chilika Lake in India. In parts of Myanmar, fishers and dolphins have a long tradition of cooperative fishing, with the dolphins driving fish toward cast nets. It is Endangered.

Island fox

The island fox lives only on six of the Channel Islands off southern California and is the smallest fox in North America, about the size of a house cat. Its numbers crashed in the 1990s, but recovery work was so successful that three subspecies were removed from the US endangered species list in 2016. The IUCN lists it as Near Threatened.

Isopod

Isopods are crustaceans with flattened, segmented bodies and seven pairs of legs. Woodlice and pill bugs are land isopods; see our pill bug profile. In the deep sea of the western Atlantic, the giant isopod typically reaches 19–36 cm (7.5–14 in), with the largest confirmed specimens around 50 cm (20 in), and can go a long time without food.

Ivory gull

The ivory gull is the only gull with pure white adult plumage and lives year-round in the high Arctic, close to the edge of the sea ice. It eats fish and crustaceans and scavenges on dead seals and whales, including the remains of polar bear kills. Its population has declined, and it is listed as Near Threatened.