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Galapagos Islands-149 | by Tristan27
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Galapagos Islands-149

A Galapagos Sealion basking in the rising sun, surrounded by Sally Lightfood Crabs, on North Seymour Island.

 

Galapagos Sea Lion

The Galápagos Sea Lion (Zalophus wollebaeki) breeds on the Galápagos Islands and – in smaller numbers – on Isla de la Plata (to Ecuador). Being fairly social, and one of the most numerous species in the Galápagos archipelago, they are often spotted sun-bathing on sandy shores or rock groups or gliding gracefully through the surf. Their loud “bark”, playful nature, and graceful agility in water make them the “welcoming party” of the islands. They are lightly smaller than their Californian relatives, Galápagos Sea Lions range from 150 to 250 cm in length and weigh between 50 to 400 kg, with the males much larger than females. Adult males also tend to have a thicker, more robust neck, chest, and shoulders in comparison to their slender abdomen. Females are somewhat opposite males with a longer, more slender neck and thick torso. Once sexually mature, a male’s sagittal crest enlarges, forming a small, characteristic bump-like projection on their forehead. Galápagos Sea Lions, compared to California sea lions, have a slightly smaller sagittal crest and a shorter muzzle. Adult females and juveniles lack this physical characteristic altogether with a nearly flat head and little or no forehead. Both male and female sea lions have a pointy, whiskered nose and somewhat long, narrow muzzle. The young pups are almost dog-like in profile. Another characteristic that defines the sea lion are their external ear-like pinnae flaps which distinguish them from their close relative in which they are often confused with, the seal. The fore-flippers have a short fur extending from the wrist to the middle of the dorsal fin surface, but other than that, the flippers are covered in black, leathery skin. Although somewhat clumsy on land with their flippers, sea lions are amazingly agile in water. With their streamline bodies and flipper-like feet, they easily propel themselves through crashing surf and dangerously sharp coastal rocks. They also have the ability to control their flippers independently and thus change directions with ease and have more control over their body on land. When wet, sea lions are a shade of dark brown, but once dry, their color varies greatly. The females tend to be a lighter shade than the males and the pups a chestnut brown. Born with a longer, brownish-black lanugo, a pup's coat gradually fades to brown within the first five months of life. At this time, they undergo their first molt resulting in their adult coat. Feeding mostly on sardines, Galápagos Sea Lions sometimes travel ten to fifteen kilometers from the coast over the span of days to hunt for their prey. This is when they come into contact with their biggest predators: sharks and killer whales. Injuries and scars from attacks are often visible. Galápagos Sea Lions are especially vulnerable to human activity. Their inquisitive and social nature makes them more likely to approach areas inhabited by humans, and thus come into contact with human waste, fishing nets, and hooks. They occupy many different shoreline types from steep, rocky cliff sides to low-lying sandy beaches. To avoid overheating during the day, sea lions will take refuge from the sun under vegetation, rocks, and cliffs, and wade into tidal pools. Not only are sea lions social, they are also quite vocal. Adult male Galápagos Sea Lions often bark in long, repeated sequences that are loud and distinctive. Females and juveniles do not produce this repetitive bark, but both sexes and the younger pups will growl. From birth, a mother sea lion recognizes her pup’s distinct bark and can pin point it from a crowd of thirty or more barking sea lions. On land, sea lions form colonies at their hauling-out areas. Adult males known as Bulls are the head of the Colony, growing up to 7 ft (2 m) long and weighing up to 800 lb (363 kg). As males grow larger, they fight to win dominance of a harem of between 5 and 25 cows and the surrounding territory. Swimming from border to border of his colony, the dominant bull jealously defends his coastline against all other adult males. While patrolling his area, he frequently rears his head out of the water and barks, as an indication of his territorial ownership. The average dominant bull holds his territory for only a few months, until he is challenged by another male. On land, these fights start by stretching out the neck and barking in attempt to test each other’s bravery. If this isn’t enough to scare the opponent off, they begin pushing each other and biting around the neck area. If males weren’t equipped with a thick, muscular neck, their vital organs would be easily damaged during these fights. Blood, is often drawn, however, and many male sea lions have battle scars due to these territorial competitions. Losers are dramatically chased far from their territory by the new dominant bull with much splashing. Because there is only one male in each harem, there is always a surplus of “bachelor” male sea lions. They usually congregate fairly peaceably on less favorable areas of the coastline in “bachelor colonies.”. Because the dominant male of the harem cannot feed while defending his colony, he eventually becomes too tired and weak, and is overpowered by the well-nourished, fresh bull. Breeding takes place from May all the way through to January. Because of this prolonged breeding season and the extensive care required by the pups from their mother, there are dependent pups in the colonies year round. Each cow in the harem has a single pup born a year after conception. After about a week of continuous attention from birth, the female returns to the ocean and begins to forage, and just a week after that, the pup will follow her and begin to develop its swimming skills. When the pup is two to three weeks old the cow will mate again. The mothers will take the young pups with them into the water while nursing until around the 11th month when the pups are weaned from their mother’s milk and become dependent on their own hunting skills. The pups have a strong bond with their mother. The cow will nurture a pup for up to three years. In that time the cow and the pup will recognize each other's bark from the rest of the colony. Within the colony sea lion pups live together in a rookery. Pups can be seen together napping, playing, and feeding. It is not uncommon to see one cow 'baby-sitting' a group of pups while the other cows go off to feed.

 

Sally Lightfoot Crab

The crab Grapsus grapsus (known variously as "red rock crab", "abuete negro", and, as "Sally Lightfoot") is one of the most common crabs along the western coast of South America. It can also be seen along the entire coast of Central America and Mexico, and nearby islands. It is one of the many charismatic species that inhabits the Galápagos Islands, and is often seen in photos of the archipelago, sometimes sharing the seaside rocks with the marine iguanas. The Sally Lightfoot is a typically-shaped crab, with five pairs of legs, the front two bearing small, blocky, symmetrical chelae. The other legs are broad and flat, with only the tips touching the substrate. The crab's round, flat carapace is just over 8 cm (3 inches) in length. Young Sally Lightfoot’s are black or dark brown in color and camouflage well on the black lava coasts of volcanic islands. Adults are quite variable in color. Some are muted brownish-red, some mottled or spotted brown, pink, or yellow. Sally Lightfoot crabs are thought to have been named for a sultry nightclub dancer from Guayaquil, whose alluring performances in her red and yellow dress, captivated 19th century sailors. This crab lives amongst the rocks at the often turbulent, windy shore, just above the limit of the seaspray. It feeds on algae primarily, sometimes sampling plant matter and dead animals. It is a quick-moving and agile crab, and hard to catch, but not considered very edible by humans. It is used as bait by fishermen.

 

North Seymour Island.

Separated by a thin strait north of Isla Baltra and Isla Santa Cruz, Isla Seymour is often referred to as North Seymour Island, while Isla Baltra is often called the South Seymour Island. Having similar flora and vegetation such as the Prickly Pear Cacti and salt bushes, Isla Seymour is very similar to Isla Baltra because they have both been created from a geological uplift. Quite a small island in terms of land mass, Isla Seymour is definitely worth visiting. To explore the island, follow a circular trail roughly 2 km long leading inland and along the rocky coast that will take you through some of the biggest sea bird breeding colonies in the entire Galapagos. Here you will find birds nesting, mating and rearing their chicks all year round. Blue-footed Boobies and Frigate birds are the main attractions here. Since most of the wildlife and birds in the Galapagos Islands are quite fearless, it is possible for visitors to get an up close view of the nests of many of the birds here, including the lovely Swallow-tailed Gulls and bright Yellow Warblers.

 

Galapagos Islands

The Galápagos Islands (official name: Archipiélago de Colón; other Spanish names: Islas de Colón or Islas Galápagos) are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, some 900 km west of Ecuador. It is a UNESCO World Heritage site: wildlife is its most notable feature. Because of the only very recent arrival of man the majority of the wildlife has no fear of humans and will allow visitors to walk right up them, often having to step over Iguanas or Sea Lions.The Galápagos islands and its surrounding waters are part of a province, a national park, and a biological marine reserve. The principal language on the islands is Spanish. The islands have a population of around 40,000, which is a 40-fold expansion in 50 years. The islands are geologically young and famed for their vast number of endemic species, which were studied by Charles Darwin during the voyage of the Beagle. His observations and collections contributed to the inception of Darwin's theory of evolution by natural selection.

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Taken on April 18, 2009