National Geographic : 1988 Jan
lizards swim furiously, going nowhere. A smaller subspecies of the California sea lion, about 50,000 of the Galapagos variety live in groups composed of a bull, weighing as much as 250 kilograms (550 pounds), and perhaps 30 cows. Such groups are called harems, although cows often change territories. Only five other mammal species ZALOPHUSCALIFORNIANUSWOLLEBACKI are native to the islands-fur seals, two bats, and two rodents - probably because others could not survive a long trip on a mat of debris from the mainland.