We explain everything about dolphins, where they live, what they feed on and how they reproduce. Also, what types of dolphins exist.
What are dolphins?
The Dolphins They are cetacean mammals of aquatic life, inhabitants of seas and rivers Depending on the species, they are among the most intelligent animal species on the planet.
In general, when we think of dolphins we refer to the 37 species that make up the oceanic variant (of the family delphinidae), who inhabit the sea surface and maintain frequent and friendly relationships with humans, despite the fact that they are often accidental victims of their commercial and fishing activities.
Dolphins are, from a zoo point of view, little more than toothed whales, that is, marine mammals that returned from the mainland to marine life, sometime in the Miocene, 23 million years ago, when they presented the necessary evolutionary adaptations for this. It is thought that the common ancestor between dolphins and land-based animals was a species of artiodactyls, that is, prehistoric hippos.
Dolphins are considered friendly and intelligent in most cultures. In fact, they are sociable animals, perfectly trainable, which nowadays are a regular part of shows and water parks.
Its presence in ancient mythological accounts is common in maritime cultures, such as the Greek, in which it was said that they had been pirates, transformed into fish by the god Dionysus after they tried to sell him as a slave. In his depictions of Poseidon, god of the seas, he is often surrounded by seahorses and dolphins.
See also: Sea animals
Dolphin characteristics
Broadly speaking, dolphins are characterized by the following:
- They are mammals of aquatic life, that is, they have a body adapted to water (with fins instead of legs), but at the same time breathe the air and have warm blood. They are not fish.
- They have a torpedo-shaped body, ideal for swimming at high speeds, which begins with a thin and serrated snout, and culminates with a powerful tail that has a caudal fin, with which it propels itself.
- His skin is gray-blue, darker on the back and lighter on the belly, free of any form of fur. Different species may have characteristic colored spots and lines.
- They have a large brain, with a highly developed cerebral cortex, compared to the average of mammals, which allows complex social interaction: playing, communicating, teaching their young, cooperating, planning and suffering.
- Given whate are able to establish strong social tiesThey can be found in large groups of up to 1000 individuals, in which the sick are cared for and attended to.
- Manage a complex echolocation system, emitting sounds in a burst to perceive the echoes that are returned, like a radar. In this way they can perceive potential prey and monitor the environment around them. For this they have an organ called “melon” in their heads.
- The Dolphins are able to vocalize a very wide range of soundssuch as hisses and clicks.
Where do the dolphins live?
Dolphins commonly inhabit the surface regions of seas, rivers and lakes, depending on the family and the species. They live their entire lives in the water, without the need to venture onto the mainland, and they always prefer the warm waters of the tropics and surrounding regions.
What do dolphins eat?
The Dolphins they are carnivores, and their diet consists of small fish and squid. They are intelligent hunters, who have very varied strategies to isolate their prey from the shoal or to ambush them.
How do dolphins reproduce?
As with mammals in general, the reproduction of dolphins is sexual and viviparous, with internal fertilization of the female by the male.
Intercourse occurs from the front, lasts little and is repeated several times, after a courtship in which the male plays striking sounds for the female, swimming around her. Dolphin gestation lasts about a year, although in some species it can last a year and a half, and in the end there is only one young per parturition.
How long do dolphins live?
The life expectancy of dolphins can be around 20 and 30 years, and spread further in ideal captive conditions. In the wild, this species does not have great predators or threats.
However yeah are threatened by humans, due to environmental contamination by pesticides, heavy metals and plastics, or accidental fishing in the middle of schools of commercial fish (such as tuna). There are also some countries in which the dolphin is part of the traditional gastronomy, such as Japan and the Faroe Islands.
Types of dolphins
There are two “types” of dolphins, with different habitats and different characteristics, since they are two different superfamilies, each one comprising a different set of species:
- Oceanic dolphins or dolphins, typical sea dolphins, coastal inhabitants that interact a lot with humans, like the common dolphin in the movies.
- River dolphins or platanistoids, inhabitants of estuaries and rivers, with a long trunk (almost 60 cm) and smaller body size, such as the dolphin or Amazon dolphin.