A plethora of insects, invertebrates and fish inhabit the Galapagos Islands. In fact, more than 1,700 species—two-thirds of the invertebrates living here—are insects. Ten species of butterflies comprise the most showy insects on the archipelago, but there are also ants, beetles, centipedes, dragonflies, grasshoppers, spiders and scorpions, among others. Tide pools reveal a variety of invertebrates including crabs, starfish, anemones, lobster, sea urchins and corals, while the water, which fluctuates between temperate and tropical temperatures, rewards visitors with a mix of diverse fish that include sharks, rays, stingrays and colorful tropical fish like the blue parrotfish and white-banded angelfish.
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Insects | Invertebrates | Fish
Insects are the most numerous animals in existence. Literally millions of species are found in the tropics, a little over 1,000 of which are thought to inhabit the Galapagos. This comparatively small number is very reflective of the difficulty that insects had in crossing the almost 620 miles of ocean to colonize the islands.
There are not many colorful insect species in the Galapagos. There are a few species of butterflies, ants, grasshoppers and wasps, and many more representatives of the beetle and moth groups. There is also only one species of bee, one preying mantis and two scorpions in the Galapagos. The scorpions are rarely encountered and though their sting can be painful, they are not normally dangerous.
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In terms of invertebrates (animals lacking a backbone), most visitors first notice a small crab with a bright red top and blue underside because the Sally Lightfoot crab is ubiquitous on most rock beaches. Also present on rock beaches is a black crab, which blends well with the lava background. These small, well-camouflaged crabs are actually young Sally Lightfoots. The adults, however, are far from camouflaged and must remain alert and vigilant to escape predators. If humans approach them, Sally Lightfoots will immediately dash to safety and are even able to scurry across tide pools by staying on top of the water. If you remain still crabs will draw near, a fact that herons, who prey on Sally Lightfoots, use to their advantage during predation. Keep an eye out for a lava heron waiting motionless amid rocks on the beach. If a crab moves within striking distance, the bird will thrust toward the crab to grab it. If the heron succeeds, he will devour it, but only after shaking it and knocking it against rocks to make its legs fall off.
Other crab species inhabit the Galapagos, including the ghost grab, a pale, sand colored creature that stares at you with unusual eyes situated at the terminus of long eyestalks. It leaves a characteristic pattern of sand balls that are seen on most sandy beaches.
Tide pools also support the hermit crab, a crustacean who makes its home by carrying an empty seashell on its back. When a juvenile hermit crab outgrows its protective shell, it finds a larger one and grows into that one. This “moving house” occurs several times before the hermit crab reaches adult size.
At low tide, tide pools offer a good opportunity to study marine invertebrates. Starfish, sea anemones, sea urchins, marine snails, barnacles, chitons and limpets are often found. Venture deeper into the water with snorkeling gear to see many more creatures, including sea cucumbers, octopus and corals. If you poke around some of the rocky underwater crevices, you may even encounter lobster. Be careful where you poke though, because you may encounter the sea urchin, which has beautiful iridescent black spines that are long, brittle and needle-sharp.
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Scientists have recorded over 300 species of fish from more than 90 families in the Galapagos, and it is expected that there are still more waiting to be discovered. Over 180 of these fish are found in much of the tropical eastern Pacific, and about 50 species are endemic. Godfrey Merlen’s Field Guide to the Fishes of Galapagos is available in Quito, and is highly recommended for snorkelers. This booklet describes and illustrates over 100 of the most frequently seen species. One interesting fact that you may read is that many species of tropical fish change their color and shape as they age; a few can even change their sex midway through life. This certainly makes identification confusing!
Snorkeling in the Galapagos is a rewarding experience, with schools containing thousands of tropical fish routinely seen. Your naturalist guides can help to identify the more common species. These include blue-eyed damselfish, white-banded angelfish, yellow-tailed surgeonfish, moorish idols, blue parrotfish, concentric puffer fish, yellow-bellied triggerfish and hieroglyphic hawkfish, to name but a few, and to give you some idea of the variety in form and color.
The one type of fish that swimmers are often most interested in is the shark. There are several species found here, the most common of which being the white-tipped reef shark and the Galapagos shark. Hammerheads are also occasionally seen. Sometimes viewed by snorkelers, their speed and grace underwater is extraordinary. In fact, one of the best reasons to snorkel in the Galapagos is the chance of seeing these magnificent animals.
Another kind of fish that provides the snorkeler with a real thrill is the ray. Again, there are several species, all harmless with the exception of the stingray, which sometimes basks on the sandy bottoms of the shallows and can inflict an extremely painful wound to waders and paddlers. It is a good idea to enter the water by shuffling your feet along the sandy bottom. This gives stingrays the chance to swim away before you step on them. Less frequently seen is the giant manta ray, which is usually found in deeper offshore waters. You are most likely to catch sight of one as it leaps out of the water and falls back with a loud slap. With a maximum spread of 20 feet, it makes a huge splash as it hits the water.
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