Las Bachas, isla Santa Cruz, islas Galápagos, Ecuador, 2015-07-23, DD 23. 10 million years ago, which is older than any of the extant Galápagos islands. Early visitors to the Galápagos Night of the iguana pdf considered the marine iguanas ugly and disgusting.
The guanas are small, and of a sooty black, which, if possible, heightens their native ugliness. Indeed, so disgusting is their appearance, that no one on board could be prevailed on, to take them as food. I call them ‘imps of darkness’. They assuredly well-become the land they inhabit. The marine iguana lacks agility on land but is a graceful swimmer.
Its laterally flattened tail and spiky dorsal fin aid in propulsion, while its long, sharp claws allow it to hold onto rocks in strong currents. Adult males vary in colour with the season, becoming brighter when breeding. There are also major differences in the colour of the adult males depending on subspecies. Females show much less variation between the islands and are typically dark with less contrasting colours than the males.
There are major differences between the islands. Other subspecies are of intermediate size, in between the small Wolf, Darwin and Genovesa iguanas and the large Santa Cruz, Isabela and Fernandina iguanas. This difference in body size of marine iguanas between islands is due to the amount of food available, which depends on sea temperature and algae growth. There is a correlation between longevity and body size, particularly for adult males. This results in large males suffering higher mortality than females and smaller adult males. The mortality rates of marine iguanas are explained through the size difference between the sexes.
December to March and nesting from January to April. The exact timing depends on the island. Sexual maturity is marked by the first steep and abrupt decline in bone growth cycle thickness. Males are selected by females on the basis of their body size. Females display a stronger preference for mating with bigger males. It is precisely because of body size that reproductive performance increases and “is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males. During courtship, the male nods at the female and if she accepts the male mounts her while holding her by the neck.