Dispersal

All of the plants and animals that live in the Galapagos Islands today are descendants of those that arrived from elsewhere - after all, when the newly formed volcanic islands of Galapagos first rose above sea level millions of years ago, they would not have had any animals or plants living on them then!

Bats, insects, birds and some plant seeds arrived in Galapagos by air, either flying or drifting on the wind. Some animals may have floated across the ocean to the islands on rafts of vegetation, eventually reaching land. Reptiles are able to survive long sea journeys because they are cold-blooded, so they don't need to eat very often, while land mammals can only survive short crossings, which explains why there are many more reptile species in Galapagos!

REPTILES

There are 23 species of land reptiles that live in the Galapagos Islands: 3 species of iguana, 7 lava lizards, 9 geckos, 3 snakes and 1 species of giant tortoise (the giant tortoise has evolved into 14 different races!)

The Galapagos Giant Tortoise can have 3 different shaped shells: the smaller saddleback (the shell is raised in the front), the dome shape (a larger and heavier domed shell), and then intermediate between these two shapes and sizes. Tortoises eat great quantities of grass, leaves and cactus pads. There are only about 15,000 tortoises left in Galapagos; 3 races are now extinct and only one tortoise is alive from the fourth race - his name is Lonesome George.

Marine iguanas are the only sea-going lizards in the world, living on land but graze on seaweed on coastal rocks or in the sea. There are 2 species of land iguana, one living only on Santa Fe island and the other on six of the central and western islands. Iguanas are cold-blooded and need to regulate their body temperature by moving in and out of the sun.

MAMMALS

Native and mammals are rare in the Galapagos Islands, and include only those which could make the long journey from the South American continent - bats which flew, rats which probably arrived on floating vegetation, and sea lions which could swim to the islands.

Native Galapagos mammals

Galapagos sea lion
Colonies of the sea lions are found on most gently-sloping rocky shores and beaches in Galapagos. The males are larger than the females, and can weigh up to 250 kg. There are about 50,000 sea lions in the islands, and they eat mainly fish.

Galapagos fur seal
The fur seals are smaller than Galapagos sea lions, weighing up to 68 kg. They have large eyes that help them hunt for squid and fish at night.

Rice rats
Only three species of rice rat still survive, and scientists think that up to seven species of rice rats have become extinct in Galapagos. Rice rats eat mainly plants, and are most active during the night.

Galapagos red bat
Not very much is known about the life cycle of the Galapagos red bat, but they are thought to be active at night when they feed on insects, and roost in mangrove trees during the day. Another bat found in Galapagos, the hoary bat, is also common in North America.

INSECTS, SPIDERS AND SCORPIONS

There are over 1600 species of insects in the Galapagos Islands, although many kinds that are common elsewhere in the world are missing, such as stick insects and mayflies. This may be because they did not disperse successfully to the islands. Some of the common insects in Galapagos include:

• Painted locust
• Carpenter bee
• Sulphur butterfly
• Green hawkmoth

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