INTRIGUING ANIMALS 1: THE MARINE IGUANA
The world is full of so many wonderful creatures, some friendly ones, some dangerous ones, some whose appearance are fear instilling, while they are harmless, and some that apppear harmless, but are very dangerous. So many also abound that would rouse your curiosity the moment you see them.
Some of these creatures today are either endangered, or even completely extinct either due to man's explorational activitivities, thereby destroying their natural habitat, or because they became prey and food to other animals including man.
Today I want to look at one intriguing creature, THE MARINE IGUANA, a member of the reptile family that has been around for millions of years of years now.
ORIGIN AND APPEARANCE:
The Marine Iguanas (Amblyrhynchus cristatus), is the only living specie of marine lizard on earth, they grow to length of about 4 - 5 feet (1.2m - 1.5m) and weigh between 0.5kg - 12kg. They are found only on the Galapagos Islands of Baltra, Daphne, Darwin, Marchena, Pinzon, Rabida, Santa Fe, Seymor, Sin Nombre and Wolf, off the coast of Ecuador, and have adapted well to the harsh marine conditions. Because they are found only on the Galapagos Islands, they are also called Galapagos Marine Iguana.
They are dark grey to completely black in colour, though during the mating season they may produce some blotches of green and red most especially the male. Due to the fact that they are cold blooded, their dark skin helps them absorb a lot of heat from the sun when they bask in the sun, and this helps them a lot when they dive into water.
At a glance, they resemble large lizards, though they have blunt noses for grazing on seaweed, laterally flattened tails to assist swimming, and powerful sturdy limbs with strong claws to help them cling to rocks. And they have these cool looking crested spikes that are seen all throughout the neck to the end of the tail. The marine iguanas, unlike most other lizards have heavy body.
BEHAVIOUR:
Marine iguanas are active during the day and spend the first few hours after sunrise basking in the sun in preparation for activity. They majorly feed almost exclusively on marine algae in the intertidal zones during low tide, especially the young and the female ones, only the largest ones, which are always adult males dive into the water, up to a depth of 25 to 30 meters in search of food, mostly during the hot midday hours, and they spend between 30 and 40 minutes underwater during each dive.
The waters are extremely cold, and this makes the iguana to lose body heat rapidly while feeding. They however deal with this by slowing down their heart rate thereby reducing the level of blood circulation in order to prevent heat loss. The heat loss, however forces them to return to the shore and bask in the sun, so as to return to their normal body temperature, before returning for another round of feeding.
A marine iguana's size determines the way it retains or loses heat and its method of feeding. Smaller individuals, lose heat quicker and forage on rocks at low tide, scraping algae off the surface, and rarely dive into the sea. Larger individuals, lose heat at a much slower rate and so they can be active for a longer period of time, they graze seaweeds in the shallow water around two to five metres in depth but can dive up to 25 metres down to rocks where there is an abundance of algae, and no competition from other iguanas.
While feeding iguanas consume a great deal of salt water excess of it can be toxic. They therefore excrete concentrated salt crystals from a nasal gland by sneezing. The salt crystals excreted covers their head like a wig and also helps in preventing heat loss.
By late evening there is minimal or no activity again and just before sunset, the iguana retreats into crevices or beneath boulders for the night.
The iguanas lives in colonies outside the breeding season, they gather around to bask in the sun, some even climb on each others back to get the heat from the sunlight, but during the breeding seasons, the male iguanas become very territorial.
Adult male iguanas defend there mating territories, they drive off other male iguanas by raising its body on legs while moving the head. Adult males are also involved in head-on push just to claim their territories. They hardly fight just to conserve energy, but when they do, they use less energy consuming charges and bites to protect their territory.
FEEDING:
A marine iguana, feeding underwater
Marine iguanas feed on seaweed and other marine algae. They consume as many as 4 to 5 different species of algae, but they prefer the red and green algae but they mostly rely on green algae because red algae is too scarce.
Unlike females, adult males will go for algae offshore and so they don’t face any competition from young iguanas or females. The given temperature and the season determine the foraging behavior of marine iguanas. They might not swim if the tides are too high but once the tides go down, iguanas are likely to go into the water to feed on seaweed that are on the shores and reefs.
The strong and very sharp claws of the marine iguana used for grasping underwater rocks
Iguanas have very strong and sharp claws, and this makes people to assume that they are carnivorous, they are not carnivores, they only use their claws to grasp firmly onto rocks so as not to be disturbed by the surf, they also use the claws to scrape off algaes from underwater rocks.
SWIMMING:
It is quite a sight to watch a marine iguana swim. They tuck their front legs under their bellies and point their back legs straight back. Their flattened tail serves as a propeller that helps them wade through the water, as they twist their whole bodies back and forth in line with their tails. The spikes from the back of their heads all down to the end of their tail the is raised slightly, hence creating a dorsal fin.
REPRODUCTION:
Marine Iguanas breed every year during the breeding season which normally starts in December and occurs over a three to five month period, and during this season, the males become very territorial, defending their mating territories.
Individuals breed normally just once every two years.
A brightly coloured adult male trying to attract a female during the breeding season
During the breeding season, the male marine iguanas produce bright colours, so as to attract female counterparts, these colours most times are red, green, blue and any other colour.
After mating, the nesting months are January through to April depending on the island. Females go up to 300 meters inland where they make burrows between 30 to 80 centimeters deep, in sand or volcanic ash and lay their eggs. They lay between one and six eggs, and would stand guard over the burrow for days before they then leave their eggs to finish incubation, which takes betwee 90 and 110 days.
When they hatch, the young marine iguana does not receive any parental care as they already look like miniature adults and act like adults too.
PREDATORS:
The Galapagos hawk and the great blue heron are the natural predators of the marine iguanas. Galapagos hawks hunt the full grown iguanas, while the blue herons eat the small hatchlings.
However, the marine iguanas to some extent depend on mockingbirds, to avoid being eaten by Galapagos hawks; whenever a Galapagos hawk is in the area, the mockingbird lets out a distinctive cal, marine iguanas recognize this call and run for cover.
Sharks and gulls also prey on marine iguanas.
Another set of predators that pose a threat are what i call the human induced predators, and they are the dogs and cats. I call them human induced because these are pets that were brought by the settlers on the islands. n short, humans. Feral dogs and cats attack the iguanas and their nests, thereby posing a great threat.
DO YOU KNOW:
Marine iguanas do not have gills and so they don't breathe underwater, rather when they dive under water, they hold their breathe until the come back on shore.
Marine Iguanas can hold their breathes for 30 to 40 minutes and sometimes they even go more than that.
All hail the marine iguana, the only lizard/iguana that feeds in the ocean, all hail the only marine lizard, all hail this beautiful creature.