Dolphins of Costa Rica

Several types of dolphins can be found in the ocean waters off Costa Rica’s shores.  While the killer whale (not really a whale), bottlenose and spotted dolphins are the most common, the rough-tooth and risso dolphins, pilot whales, pseudo orcas (false killer whales) and melon-headed whales are also somewhat commonly sighted.

Bottlenose Dolphins:

Bottlenose dolphins are commonly sighted along both of Costa Rica’s coasts.  They are characterized by their long, beak-like snout.  They range in size from 8.2 feet to more than 12 feet in length and can weigh as much as 1000 lbs.  Males are typically longer and heavier as adults, but the females tend to grow more quickly as juveniles until about 10 years in age.

Their bodies are gray to gray-green on the back, fading to white or light pink on the belly. 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 color of the belly blends with the bright surface of the sea.  When viewed from above, the dark back blends in with the color of the ocean and the depths below.  Older animals sometimes have spotting along their sides and bellies.

They have a very well developed and acute sense of hearing and eyesight, but a limited sense of smell. They breathe through their blowhole and hold their breath while under water.

Bottlenose dolphins live in groups called pods and are very social animals, actually having preferences as to with whom they hang out.  They develop strong social bonds, hunt, feed and play together.  They spend about 33% of their day sleeping.  They are active predators eating a wide variety of fish and crustaceans, averaging a total daily consumption of 4-5% of their body weight.

Bottlenose dolphins inhabit temperate and tropical waters throughout the world in a variety of locations including pelagic zones as well as harbors, bays, lagoons, gulfs, and estuaries.  Dolphins of colder climates demonstrate a clear tendency toward seasonal migration, which is highly dependant on food availability.  Those in warmer waters like those in Costa Rica, show less extensive, localized seasonal movements.

Fortunately, bottlenose dolphins are not endangered and some populations are even growing in number.

The Killer Whale:  

The killer whale, the largest member of the dolphin family, weighs between 4-8 tons with length of 22 to 30 feet, with the males typically being larger than females.  Killer whales do not migrate like the humpback whale, but do have seasonal movements related to prey and other environmental factors. They live in pods of 5 to 70 individuals and are thus very social animals. 

Killer whales have a wide variety of behavior ranging from transient groups to residential and offshore pods.  Transient groups travel long distances in unpredictable patterns and smaller numbers feeding on other mammals, while the resident groups tend to travel in more predictable locations, eat mostly fish and tend to be more vocal.  Transient dolphins have a distinctly more pointed dorsal fin and are less vocal than the resident groups.  The rarely seen offshore groups travel in large numbers (up to 70) and feed on squid and fish. 

Though not technically endangered, some groups are threatened.  The transient killer whales are considered one of the most polluted animals on earth because PCB’s tend to collect in their blubber as a result of eating contaminated fish.

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