Galápagos sea lions (Zalophus wollebaeki) are the smallest sea lion species and one of the most numerous species in the Galápagos archipelago. They are fairly social and can often be spotted sunning on sandy shores or rocks or gliding through the surf.
Di
DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
Ca
CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
Pi
PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
Mo
MolluscivoreA molluscivore is a carnivorous animal that specializes in feeding on molluscs such as gastropods, bivalves, brachiopods, and cephalopods. Known mo...
Se
SemiaquaticSemiaquatic animals are those that are primarily or partly terrestrial but that spend a large amount of time swimming or otherwise occupied in wate...
Pr
PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Na
NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
Te
TerritorialA territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
Te
TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Co
CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Vi
ViviparousAmong animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
So
SocialDo
Dominance hierarchyA dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social gr...
No
Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
G
starts withMale Galápagos sea lions are larger than females. Adult males also tend to have a thicker, more robust neck, chest, and shoulders in comparison to their slender abdomen. Females, by contrast, have a longer, more slender neck and thick torso. The male's sagittal crest enlarges when he reaches reproductive maturity, forming a small, characteristic bump-like projection on his forehead. Adult females and juveniles lack this trait and have a nearly flat head and little or no forehead. Both male and female sea lions have a pointy, whiskered nose and long, narrow muzzle. Young pups are almost dog-like in profile. Another characteristic that defines the sea lion is the pinnae of the external ears, which distinguish them from seals. The foreflippers 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. Curving posteriorly, the first digit of the flipper is the largest, giving it a swept-back look. At the end of each digit is a claw, usually reduced to a vestigial nodule that rarely emerges above the skin. 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. Pups are born with a longer, brownish-black lanugo that gradually fades to brown within the first five months of life. At this time, they undergo their first molt, resulting in their adult coat.
Galápagos sea lions can be found on each of the islands of the Galápagos archipelago. They have also colonized just offshore the mainland Ecuador at Isla de la Plata and can be spotted from the Ecuadorian coast north to Isla Gorgona in Colombia. They have also been spotted on Isla del Coco Island, which is about 500 km southwest of Costa Rica. Less than a quarter of them reside on the most tourist drawn area, San Cristobal Island. 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.
Galápagos sea lions are very social and on land, they form colonies in their hauling-out areas. Adult males are the head of the colony. As they grow, they fight to win dominance of a harem of between five and 25 cows, and the surrounding territory. Males in this species are two types: territorial and non-territorial. Territorial males vocalize at higher rates and vocalization is important to them because it plays a key role in the selection of female and helps ward off intruding non-territorial males into their harem. The average dominant bull holds his territory for only a few months until he is challenged by another male. 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 cannot feed while defending his colony, he eventually becomes too tired and weak and is overpowered by a well-nourished, fresh bull. Galápagos sea lions become active at sunrise when the dominant bull first enters the water to feed followed by the rest of the group. Most of the time is spent in the water hunting, or just to cool down from the heat. They rarely travel far from the shore and, when threatened will flee from the water as quickly as possible. The rest of the time they spend on the beach. Galápagos sea lions are quite vocal. Adult males often bark. Females and juveniles do not bark, but both sexes of younger pups growl. From birth, a mother sea lion recognizes her pup’s distinct bark and finds her offspring from a crowd of barking sea lions.
Galápagos sea lions are carnivores (piscivores) and feed mostly on sardines. They also eat fish, squid, octopus, and crustaceans.
Little is known about the mating system in Galápagos sea lions. Breeding usually takes place from May through January. Each female in the harem has a single pup born after the gestation period that lasted 11 months. 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 2-3 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. At this time the pups are weaned from their mother’s milk and become dependent on their own hunting skill. The age of maturity for Galápagos sea lions is reached when they are 4 to 5 years old.
During El Niño events, the population of these animals tends to decrease as ocean temperatures warm and cold-adapted marine life on which the sea lions depend declines, which lead to die-offs. Sharks and killer whales are the main predators of the sea lion, especially little pups are easy targets. As the human population continues to grow it nevertheless presents various risks for accident and disease. The sea lions have learned that being near the fisheries they have a better chance at capturing fish with little to no work, but as a result, they are in more danger from boats and net entanglement. They are impacted by humans indirectly as well. Stray dogs introduced by humans form packs and attack sea lions. The pesticide DDT, still in targeted use to prevent malaria in tropical countries, accumulates through the food chain and is found at near-toxic concentrations in sea lion pups.
According to the IUCN Red List, the total population size of Galápagos sea lions is around 9,200-10,600 mature individuals. Currently, this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...