Finless Porpoise

The finless porpoise is a small marine mammal that can be found swimming in the coastal waters of Asia primarily in the Yangtze, Western Pacific and Indian Oceans.

This porpoise makes up one of six species of porpoise and belongs to the group known as Cetacea, which includes all species of whaledolphin and porpoise and is divided into two suborders known as the toothed whale and baleen whale suborders based on the animals characteristics.

All species of porpoise fit into the toothed whale suborder due to their presence of teeth.

As the name suggest the finless porpoise is completely finless with a flat back.

Instead of a large fin it has a small hump or ridge with small bumps known as  tubercles that are visible on the middle of its back.

Physical Characteristics and Appearance

The finless porpoise is mostly a grayish color although it appears black at the time of birth.

After several months the dark coloring of the porpoise begins to fade and after six months it is almost completely gray.

Adult porpoises can reach an average height of around 5 – 6 ft in length and weigh as much as 100 pounds, however their skeleton is relatively light accounting for only 4 – 6 percent of their total body weight.

In terms of shape the porpoises body is somewhat stocky but tapers down towards the flukes and the head is bulbous shaped and lacks a beak as is common with the porpoise species.

Diet and Hunting Method

The diet of the finless porpoise can vary from one location to the next however they are primarily known for eating fish, prawn, squid, octopus and shrimp.

In addition to consuming animals these marine mammals are also believed to consume plant-life when living in environments that offer sufficient plant materials.

During long dives these marine mammals have been known to hold their breath for up to 4 minutes and often resurface at a distance from the last place they surfaced for fresh air..

Habitat and Migration

As mentioned earlier the finless porpoise can be found in various parts of Asia in the Yangtze river, Western Pacific and Indian Oceans.

Some of the most common areas these marine mammals inhibit include Bangladesh, China, India, Indonesia, Japan and Korea.

Shallow waters, swamps and etuaries are common areas where they can be found.

Limited information suggest that finless porpoises are not a migratory species and can be found living in coastal waters year round.

Social Structure and Communication

Most finless porpoises can be seen traveling alone or in small pods of up to 12.

The majority of pods traveling together often consists of 2 porpoises (a mother and her child).

In rare cases several dozen pods may be seen aggregating together (usually during times of feeding) and may form groups of up to 50.

Breeding and Reproduction

Breeding typically occurs during the spring/summer months of the year.

The gestation period (the period from conception to birth) lasts about 10 – 11 months.

After birth the child can be seen clinging onto the mothers back as she swims.

Females feed there young by producing milk from their mammary glands.

Depending on the mother and child feeding can continue anywhere from 6 months to over a year.

It is believed that sexual maturity is reached between 4 – 6 years of age and that the average lifespan ranges from 10 – 30 years depending on their health and habitat.

As stated before the mother is generally the care giver and will swim with her child until the child is fully matured.

Threats

Unlike other species of Cetacea the finless porpoise has never really been hunted by humans.

While there are a few cases of them being hunted in the early 1900’s for the most part they have remained a protected and rarely hunted species.

Since these porpoises are primarily coastal their main threats include being entangled in fishing nets, collisions with boats, noise and water pollution and the construction of damns, harbors and other man-made structures.

Due to their coastal environment, the increased threats they face and their shrinking population, the finless porpoise is currently considered vulnerable or endangered depending on where they are found.

Bycatch – Since these porpoises live in coastal waters that are frequently used by fishermen they are at risk of getting caught in submerged fishing nets which leads to drowning as it prevents them from surfacing for air.

Boat strikes – Boat strikes are also a threat as passing boats can strike these marine mammals as they travel through the water.

Pollution – Areas where construction and agricultural developments have taken place increase the risk of chemical and/or material waste exposure which can have an impact on the direct health of the finless porpoise or indirectly affect them by poisoning their habitat and food supply.

Predators

Given the habitat of the finless porpoise the most likely natural predator of these marine mammals are local sharks.

Their large size (when compared to other local ocean animals) and coastal lifestyle makes them less of a target for other potential predators.