The Galápagos Giant Tortoise - There are 11 endemic sub-species, and the males on some islands weigh as much as 600 pounds. They can live for at least 100 years, possibly a lot longer.
Since they had so much meat on them that was considered "tasty," and since they could go for months without food or water (due to their extremely low metabolism), they were hauled on board by the hundreds and stored below on pirate, whaling, and virtually all vessels. Hundreds of thousands of giant tortoises were taken from the Galápagos until their numbers were dangerously low. In order to preserve and protect the species, Ecuador declared the Galápagos to be a National Park in the 1960s. Within a few years, the Charles Darwin Research Station began its function in the islands as a research consulting organization,
to support the work of the Galápagos National Park Service. The program has been largely successful, although there have been several major challenges, such as an overpopulation of introduced goats on some of the islands - the goats would virtually denude the vegetation (the food the tortoises depended on) wherever they roamed. Other introduced animals, such as pigs and rats, would invade the nests of the tortoises and eat the eggs.
to support the work of the Galápagos National Park Service. The program has been largely successful, although there have been several major challenges, such as an overpopulation of introduced goats on some of the islands - the goats would virtually denude the vegetation (the food the tortoises depended on) wherever they roamed. Other introduced animals, such as pigs and rats, would invade the nests of the tortoises and eat the eggs.
There are 2 body types for the Galápagos Giant Tortoise - dome-shaped (above), for plowing through dense vegetation, and saddle-backed (below) for reaching higher branches, etc. in drier areas. The saddle-back was supposedly the model for E.T. That's the story anyway. A somewhat sadder story. Less than 100,000 years ago, there were giant tortoises throughout the world; now there are only two populations, one in
the Galápagos and the other on the Aldabra islands (part of the Seychelles).
the Galápagos and the other on the Aldabra islands (part of the Seychelles).
Tortoises, being reptilian, are what some call cold-blooded; scientists call them poikilothermic, meaning their temperature can vary. Mammals on the other hand are homeothermic; they keep their temperatures more or less constant (except for those that hibernate). Further, mammals are endothermic; they
maintain their temperatures internally. Reptiles are ectothermic; they control their
temperature externally, by their behavior.
Although tortoises are not fast of foot, they can get somewhere when they have to - the case of a male approaching a female would be a readily understood example. Once mating has begun, it continues for some time; interestingly, males can be 3-4 times larger than females! In a few months, the female
lays about a dozen eggs that will hatch out in a little less than a year. The gender of the hatchling
is actually controlled by the incubation temperature and not by chromosomes; the warmer the
egg during the middle trimester of the incubation period, the greater the tendency to become
a female. Or, as some the Guides say, "hot babes and cool dudes!"
maintain their temperatures internally. Reptiles are ectothermic; they control their
temperature externally, by their behavior.
Although tortoises are not fast of foot, they can get somewhere when they have to - the case of a male approaching a female would be a readily understood example. Once mating has begun, it continues for some time; interestingly, males can be 3-4 times larger than females! In a few months, the female
lays about a dozen eggs that will hatch out in a little less than a year. The gender of the hatchling
is actually controlled by the incubation temperature and not by chromosomes; the warmer the
egg during the middle trimester of the incubation period, the greater the tendency to become
a female. Or, as some the Guides say, "hot babes and cool dudes!"
On islands with highlands, they enjoy resting in pools of rainwater; here they can drink,
thermoregulate, and possibly shed parasites.
thermoregulate, and possibly shed parasites.
We do not have a way of determining the age of a given individual; it is possible that the animal was alive when Darwin visited the islands in 1835. Amazing! Equally amazing is that Giant Tortoises are very
curious creatures, which anyone who works with them will attest to.
curious creatures, which anyone who works with them will attest to.
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The Pacific Green Sea Turtle - Remember, it's tortoises on land with their ponderous elephantine-like feet (see above ) and turtles in the water (using their fins for propulsion). So when your friends ask if you went to the Galápagos to
see the"big turtles", you can set them straight.
see the"big turtles", you can set them straight.
They can rest on the bottom for several hours at a time and are actually capable of breathing through
the tail area, a process called cloacal respiration. Eventually they pop to the surface and take an
audible gasp of air.
the tail area, a process called cloacal respiration. Eventually they pop to the surface and take an
audible gasp of air.
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The female (L) has a very short tail, while the male (R) has a much longer tail, as it houses the penis.
The same is true for the tortoises. Mating is a water activity and can last for some hours.
The same is true for the tortoises. Mating is a water activity and can last for some hours.
When they are occupied feeding on algae, if you hold your body still and relax, they can get pretty
close to you without seeming to get alarmed and/ or flee.
close to you without seeming to get alarmed and/ or flee.
The Pacific Green Sea Turtle is the only vegetarian sea turtle in the world (although, truth be told, I have observed them eating jellyfish - see above).
Another oddity is the occasional yellow or orange morph Green Sea Turtle
seen below; scientists are trying to sort out their origin.
Another oddity is the occasional yellow or orange morph Green Sea Turtle
seen below; scientists are trying to sort out their origin.
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The female will come on shore to nest 4-5 times in a year, but not every year. The thought is that they nest on the same beach that they hatched on, which is quite amazing, and there is evidence to support that. They did a body pit as shown above (tourist feet useful for scale!). At the bottom of the pit, a flask-shaped egg chamber is then dug out. In 3 months or so, 80-100 hatchlings will arise and flee to the ocean as one. Only one in a hundred will make it to adulthood, due to predation in the nest by introduced and natural predators (ghost crab and hermit crab tracks can be seen), in the race to the sea, and during the growth period. Sea turtles the world over are endangered due to egg poaching, the use of the shell in jewelry making, loss of habitat, human encroachment, and worst of all from fibropapilloma tumors which seem to be infecting many species of sea turtles. A herpes virus is suspected. For now, fortunately, the Galápagos population is doing well.
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The Galápagos Marine Iguana -
the only Seafaring Lizard in the World.
the only Seafaring Lizard in the World.
The diet of the adults is algae, both green and red varieties. At low tide, the females and juveniles feed close to shore while the males can dive down several feet and graze on more abundant stands of
algae. Using the sides of their mouths, they scrape the algae with their tricuspid teeth.
algae. Using the sides of their mouths, they scrape the algae with their tricuspid teeth.
During the breeding season, which varies by island, the males develop green and red coloration, which is quite brilliant. For some reason, perhaps related to their diet, the males on Espanola (Hood) Island have these colors throughout the year; some Guides refer to them as "Christmas Tree" iguanas. During this
time of the year, the breeding males posture at each other (using rapid head bobs) and actually go
to battle at times.
time of the year, the breeding males posture at each other (using rapid head bobs) and actually go
to battle at times.
The winner will ascend to the highest point in the area and, assuming a victory pose, stand guard.
Marine Iguanas have salt glands near their nasal structures and appear to be spitting when in fact they
are excreting salt. Many of them will have salt-encrusted "foreheads" from "backspray."
are excreting salt. Many of them will have salt-encrusted "foreheads" from "backspray."
At times in the western island of Fernandina, there are vast numbers of Marine Iguanas in a coastal area with views like this. After El Niño events (1982-83 and 1997-98), the algae on which they thrive die off as
do the iguanas; their numbers can go down by 90%. A warming sea is not a pleasant thought for
these and other animals dependant on a productive ocean.
do the iguanas; their numbers can go down by 90%. A warming sea is not a pleasant thought for
these and other animals dependant on a productive ocean.
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The Galápagos Land Iguana - has the same Common
Ancestor as the Marine Iguana.
Ancestor as the Marine Iguana.
As their cousin, the Marine Iguana, the adult Galapagos Land Iguana is a vegetarian, with yellow flowers being a principal part of its diet. It will also devour cactus pads, spines and all. Some individuals will actually climb a tall cactus plant to get a meal. The iguana on the right (below) is actually a unique (much more pale in appearance) species of Land Iguana endemic to Santa Fe Island.
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During the breeding season, the male coloration becomes more intense, more coppery in appearance.
Iguanas can actually hear quite well, and their eardrum is actually visible, sometimes with some coloration.
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LAVA LIZARDS AND SNAKES
Galapagos Lizards - There are several species, some endemic to a particular island. The male (L) is larger and is multicolored during the breeding season. Their courtship behavior consists of advertising their status by doing "push-ups," with each species having a particular pattern/ sequence. The female (R) breeding coloration is a bright red throat, expanding to the head and front torso regions over the course of the breeding season.
While the principal part of their diet consists of insects, they are known to occasionally cannibalize.
In the realm of symbiotic behavior, Lava Lizards frequently climb on the head regions of Marine Iguanas and feed on insects and parasites/ dead skin, benefiting them both. Often the tail of the Lava Lizard wraps around the iguana's head like a "coonskin cap," and some Guides, myself included, call this great photo op - "Iggie Boone" It was indeed a fun job.
Galapagos Racer Snake - In the constrictor family, but it doesn't kill by constricting; it uses its rear fangs to get the job done. It's pencil-thin and not menacing to humans; this image is larger than real.