Harbour porpoise (lat. Phocoenidae) – an aquatic animal belonging to the order of cetaceans, a suborder of toothed whales. The name “porpoise” comes from the Latin words “porcus” which means “pig” and “piscus” which means “fish”. Previously ranked among the dolphin family. It differs from other members of the genus in its small size.
Description
One of the smallest marine mammals. The individuals that make up the family of porpoises are quite similar in appearance and skeleton to dolphins. They also have a fish-like body with horizontal tail fins.
For reference: The oldest fossilized remains of porpoises, found in the North Pacific Ocean, date back to the late Miocene (about 10-12 million years ago). It was around this time that the first true dolphins appeared, and the common ancestor of the two families, the Kentriodontidae, dies out shortly thereafter.
Sea pigs, although they are not able to communicate through speech, nevertheless exchange information, using various signals for this in the form of clicks and whistles. Moreover, the signals used by these animals are only impulsive in nature, at the same time, monotonal whistles are recorded in dolphins. Some types of impulse signals are needed for echolocation, while others are used to display the emotions of the individual itself. They are fast and agile swimmers, reaching speeds of up to 55 km / h (15 m / s).
Appearance
The porpoise is inferior in size to the rest of the dolphin. The length of her body usually does not exceed 2 m, and her weight is 100 kg. They have a rather powerful, stocky streamlined body, and a triangular dorsal fin is clearly visible on the back. The general body color of the harbor porpoise is bluish-gray, the fins are darker. The underside of the body is much lighter than the top, but this border is indistinct. Albinism is more common in this species than in other dolphins. It seems that the porpoise is always good-natured and peaceful. At least, this is exactly the impression produced by the expression of her muzzle with a shortened rostrum.
The head has a blunt shape, and the beak is completely absent. The teeth are sharp, there can be more than 30 of them on each jaw. With age, they can fall out and grind off.
Red Book and Number
Introduced into the QC of Russia (2001). Category: 3 – rare subspecies decreasing in numbers. It is included in the IUCN-96 Red List, Appendix 2 of CITES. Measures should be developed to prevent accidental by-catch.
Accounting 1985-1987 tentatively revealed the total number of the Black Sea porpoise about 10 thousand. There was a large population here for several post-war years, when over a thousand porpoises were caught in just one sweep, and 3-4 thousand were taken in a year. Overfishing, environmental pollution are the main limiting population factors in the Black Sea. Many of these animals die from accidentally falling into fishing nets and traps. Death in ice in the Sea of Azov causes great damage in severe winters. The list of helminths includes 3 types of tapeworms, 4 – flukes, 9 – nematodes, 2 types of worms. In the Black Sea, there is a general infestation of them with the roundworm stenurus (Stenurus ovatus), which affects the hearing of these dolphins. Captivity is poorly tolerated, nevertheless, 150 individuals of this species were not kept free in the world.
What zone does it live in
They live mainly in the shelf waters of the oceans and seas of the Northern Hemisphere, as well as off the coast of South America and Southeast Asia. They are distributed throughout the continental trail of the Black Sea, and also inhabit the deepest parts of the reservoir and often swim in areas with low salt levels. They are found in the northwestern estuaries. Sometimes you can see this mammal in the waters of the rivers located in the south. They prefer to stay in bays, bays, fjords, estuaries and lower reaches of rivers.
Fact! In March-April, some of the dolphins swim across the strait to Kerch and leave only closer to November.
Blunt-faced dolphins are found in the Sea of Marmara, small groups can be found in the Aegean, but absent in other parts of the Mediterranean.
What eats
In search of food, they are capable of plunging to 75 myrtle depths, and staying there no more than 6 – 7 minutes. Hunting area at the bottom of the bottom. The diet is very varied, here are just a few dishes from their menu, which they give their deepest preference to:
- Sea handles;
- Small fish;
- Various invertebrates;
- Squid;
- Shellfish.
She must eat more than 4.5 kilograms of seafood per day to maintain her physical shape. The size of the oral cavity is so small that it is not able to swallow even 25 cm
The common porpoise can dive to a depth of more than 200 meters in search of food. Young individuals of this species learn to hunt on their own, catching crustaceans. The featherless porpoise often eats crustaceans and squid in addition to fish.
Lifestyle
Usually porpoises are timid and shy animals. They keep singly or in small groups. It is quite difficult to see, and even more so, to pursue them, so many residents of coastal areas are not even aware of their existence. The only species that comes close to moving ships is the white-winged pig. It is a fast swimmer, and when the animal emerges, fountains of spray are noticeable. It is much more difficult to notice the emerging common or featherless species, although the first species can jump out of the water horizontally in case of strong waves or when chasing fish. The Californian porpoise is especially shy, even very few scientists had to observe it during the mating season of many species falls on a certain season – usually the end of spring – the beginning of summer. Pregnancy lasts 9-10 months, after which one cub is born. At birth, the baby’s body length is 65-85 cm and it weighs about 5 kilograms. The grown-up calf sometimes remains near the mother even after the termination of milk feeding.
White pig
The mating season for many species falls on a specific season, usually late spring or early summer. Pregnancy lasts 9-10 months, after which one cub is born. At birth, the baby’s body length is 65-85 cm and it weighs about 5 kilograms. The grown-up calf sometimes remains near the mother even after the termination of milk feeding.
Interesting Facts
- The main difference between porpoises and dolphins is that they cannot tolerate life in captivity. The maximum life span in a water cage does not exceed three years.
- They are very sensitive to the environment, mud in sea water is another reason for the death of these peace-loving animals.
- Until the middle of the twentieth century, they were massacred.
- Only in 1964, the fishing of this species was banned at the state level.
- Even today, poachers exterminate mammals, they are not even stopped by sanctions in the form of fines that must be paid to those who engage in illegal fishing.
- In 2007, at the Danish Aquarium, a wonderful phenomenon happened, in captivity, a female large porpoise brought offspring, for the scientific world it was a real event.
