Dolphins
Highlights
- Scientific Name: Tursiops truncates
- Status in the Wild: Common
- Habitat: Oceans
- Diet: Carnivore
Approximately 25 whale and dolphin species inhabit Costa Rica's oceans. Off the Pacific coast, visitors may spot bottlenose dolphins, common dolphins, pantropical spotted dolphins, Risso’s dolphins, rough-toothed dolphins, spinner dolphins, and striped dolphins. Orcas, pseudo orcas, and short-finned pilot whales – also in the dolphin family – can be found along the entire length of the Pacific coast, while Costero and bottlenose dolphins are frequently seen in Costa Rica’s Caribbean waters.
read more closeBottlenose Dolphins:
One of Costa Rica’s most frequently sighted dolphins is the playful bottlenose (Tursiops truncates), which measures 8-12 feet long and can weigh upwards of 1,400 pounds. However, most bottlenose dolphins found in Costa Rican waters are significantly smaller, weighing less than 1,000 pounds. Males are typically longer and heavier as adults, but females grow more quickly within the first 10 years.
The upper bodies of bottlenose dolphins are more flexible than those of other species, since five of their seven neck vertebrae are not fused together. Their coloration shows great variation, ranging from light gray to dark gray on their backs (near the dorsal fin), and pale pink or light gray on the belly area. This color design is known as counter-shading and is a form of camouflage. When viewed from below the surface of the water, the light belly color blends with the sea’s bright surface, and from above, the dark coloration camouflages against the ocean’s depths below. Older dolphins occasionally show spotting along their sides and undercarriage.
These highly intelligent and social mammals use distinctive whistles to communicate information to other dolphins in their group, or pod. Inshore groups usually number 10-20, while offshore pods may have several hundred individuals. Bottlenose dolphins live in open societies, and though some associations are strong – the mother-calf bond, for example – their social choices within the pod vary daily.
Female bottlenose dolphins reach sexual maturity around 5-10 years of age; males mature at 10 years. Gestation lasts for one year and calves nurse for an additional 12-18 months. The first 3-6 years of a calf’s life is spent with its mother, learning how to swim, survive, and hunt.
Bottlenose dolphins have an acute sense of hearing and eyesight, but a limited sense of smell. They are active predators with sharp, conical teeth, and consume 15-30 pounds of fish, squid and crustaceans each day. Dolphins are fast swimmers and can attain speeds of 19 miles per hour in the wild. They track their prey using echolocation and often hunt in groups, particularly near fishing boats. Bottlenose dolphins have been observed chasing schools of fish onto mud banks and slipping out of the water to eat their prey.
The species is found worldwide in temperate and tropical waters. Marine biologists believe there to be two ecotypes: coastal and offshore. Coastal bottlenose populations are often found in harbors, river mouths, estuaries, and bays. In Costa Rica, dolphins are typically spotted year-round. They live along both coasts, but are particularly common in Papagayo, Montezuma, Mal Pais, Manuel Antonio, Drake Bay, and Puerto Jimenez.
Worldwide, bottlenose dolphins are not considered endangered, though populations are close to total depletion in some areas. To protect humans and animals, it is illegal to swim with dolphins in Costa Rica.
The Killer Whale:
Orca whales (Orcinus orca), also known as killer whales, are the largest members of the dolphin family. They are easily identified by their black and white color pattern. Killer whales have huge dorsal fins that can grow six feet in males and three feet in females. Dorsal markings are unique to each orca, much like fingerprints are to humans.
Male killer whales are almost twice as large as females, measuring 32 feet long and weighing eight to nine tons (16,000-18,000 pounds). They live in small pods that consist of several females, calves, and one or more males. In some pods, calves stay with their mothers for life.
Not much is known about orca breeding habits. From the data available, marine biologists infer that mating and calving occurs year-round. Killer whales reach sexual maturity at 10-18 years of age; males are ready to reproduce when they reach approximately 20 feet in length. Gestation lasts 13-17 months and females generally calve every three to five years.
Orcas are efficient predators and hunt using echolocation. They feed on fish, squid, sharks, octopus, seals, sea birds and young whales; an adult killer whale typically eats around 550 pounds of food every day. Their sleek bodies enable swimming speeds of 30 mph.
Killer whales are divided into three distinct population types: offshore, transient and resident. Transient groups migrate long distances in unpredictable patterns and feed on a variety of marine life, including sea lions, penguins, seals, sharks and whales. Resident groups tend to live and travel in more predictable locations hunting fish. Transient orcas have a distinctly pointed dorsal fin and are less vocal than the resident groups. The rarely seen offshore orcas live in pods of up to 70 individuals and feed on squid and fish.
Killer whales are found throughout the world, but generally prefer cooler waters. Unlike many whales, orcas do not follow a set annual migration pattern; instead, they follow their food. In Costa Rica, they are most often spotted breaching along the Pacific coast, particularly the Papagayo Gulf, Jaco, Manuel Antonio, Ballena National Marine Park, Drake Bay, and Puerto Jimenez. They are also found in the waters surrounding Cocos Island National Park. In general, orcas do not venture into the Gulf of Nicoya.
Though not technically endangered, certain groups of orcas are threatened. Some killer whale populations have been found with polluted blubber, a result of PCB collection from consuming contaminated fish. As fish populations decrease throughout the world, seal and sea lion numbers also decline. Both are a substantial part of the orca diet.