Spectacled Porpoise

## Description

The spectacled porpoise (Phocoena dioptrica ) is a small to midsize porpoise indigenous to the Southern Ocean. It is one of the most poorly studied cetaceans, partly due to its remote range in the southern ocean. What little is known about this porpoise species has been gathered mainly from stranded individuals, and a few observations of living animals made at sea.

## Appearance

The species is so called due to the black eye patch, surrounded by a white ring. The Spectacled porpoise is a rarely seen and little-known animal, which have been observed only a few times. This animal is distinguished from other porpoises by its small head as well as unusual facial features and coloration. The upper-parts are black, while the under-parts are white. Small flippers of the animal are located far forward on the body. The dorsal fin is considerably large and rounded in males, being smaller and more triangular in females. The back of young porpoises is dark grey, whereas the under-parts are light grey.

## Distribution

The Spectacled porpoises are distributed across the southern Atlantic, Indian and Pacific Oceans. The Antarctic range of these animals stretches from the eastern coast of South America in the south to southern Brazil in the north. In the Pacific Ocean, the area of their distribution stretches northwards, reaching Tasmania and New Zealand. The usual habitat of the spectacled porpoise is cold ocean waters of the southern hemisphere. The animal typically occurs around offshore islands, less frequently - in the open ocean. This porpoise favors cold currents on the sub-Antarctic area such as the Falkland Current.

## Behavior

Because of being quite a rare and insufficiently explored species, little is known about the biology and habits of the Spectacled porpoise. The animal is thought to be solitary, since it is generally seen alone, though small groups, consisting of three individuals (evidently, a female, a calf and an additional adult), have also been recorded. When coming to the surface, the animal is usually hard to notice, as it raises only a small part of its body in order to breathe. When noticing an approaching boat, the porpoise immediately swims away. Presently, there is no information on the migratory behavior of this porpoise; moreover, it's unknown if the animal is migratory at all.

## Diet

There is very scarce information on the diet of the Spectacles porpoise, though the animal is thought to be piscivorous and share similar diet with other porpoises, consuming fish, squid, and crustaceans.

## Reproduction

Nothing is presently known about the mating system of this animal. Meanwhile, there is very little information on the mating behavior of the Spectacled porpoise. Thus, females are believed to give birth in early spring or summer, but there is no evidence to support this assumption. Gestation period lasts for 8 - 11 months, yielding a single baby. Females of this species are sexually mature at 2 - 3 years old, whereas males reach maturity within 4 years.

## Population

### Population threats

The Spectacled porpoise suffers from human activity along with many other cetacean species: gill nets as well as trawling and stranding pose a serious threat to the population of this animal. On the other hand, the animal is threatened by human disturbance in a form of oil and mineral exploration, while offshore pollution causes the accumulation of toxins within the animal's body.

### Population number

According to the IUCN Red List, the total population size of the Spectacled porpoise is unknown for today and the species is currently classified as Data Deficient (DD) on the IUCN Red List.

## Fun Facts for Kids

Like all porpoises (except for the Dall's porpoise), these animals possess tubercles or small bumps, which may be located either on their back or on the front edge of their dorsal fin or dorsal ridge. The purpose of these bumps is unknown, though they are thought to be associated with hydrodynamics.

The upper jaw of this porpoise holds 17 - 23 teeth, while the lower jaw has 17 - 20 teeth.

Porpoises can see. But because of the low visibility underwater, these animals use echolocation, which is a sonar system, helping them navigate the ocean and find food. They give out high-frequency clicks, which, resounding, bounce back to them and bring information on the size, location and speed of a given object in just a split second. Due to this navigation system, they are able to make a mental map of the environment, which allows them to avoid even the smallest obstacles when looking for prey.

The word 'porpoise' has Middle English origin, deriving from the word 'porpeis', which means 'sea-pig', due to which porpoise is occasionally referred to as 'sea hog'.

It is believed, that porpoises have appeared as a group of aquatic mammals approximately 15 million years ago, by which time they inhabited the northern part of the Pacific Basin. In course of time, these animals slowly evolved into the six presently existing species of porpoise.