What Is A Marine Mammal?

Definition of a mammal

What is a mammal? According to the Oxford languages dictionary a mammal is a warm blooded animal with a vertebrate, distinguished by having hair or fur. Females typically can secrete milk for nourishing their young, and give birth to live young. Mammals breathe via their lungs. 

 

 

Definition of a marine mammal 

What is a marine mammal? They must meet the prerequisites laid out for a mammal. Such as warm blooded, ability to secrete milk for their young and have hair or fur at some stage of their life, as well as breathing air through lungs, all while living depending on the ocean or aqueous environment for survival and habitat. 

Types of marine mammals 

Marine mammals rely on marine ecosystems for survival. What are the different groups of marine mammals: cetaceans, pinnipeds, sirenias, Fissipeds (sea otters and polar bears)

What is a Cetacean?

Cetacea are animals that are completely aquatic, living in an aqueous environment and can not survive on land. Coming from the order Artiodactyla, the three groups of cetaceans are: whales, dolphins and porpoises. 

What are the key characteristics of Cetaceans? 

Cetaceans are classically identified by a fully aquatic lifestyle, often have streamlined body shapes and a carnivorous diet. Cetaceans are usually large in size with few exceptions such as the Vaquita. Cetacean mobility through the water column is commonly seen via tail and fluke in an up and down movement to propel themselves through the water, unlike a fish’s lateral side to side movement. 

Cetaceans are highly intelligent, and known for complex social displays and behaviours. There are approximately 89 species of living cetaceans. These 89 cetaceans can be split into Mysticetes (baleen whales such as the blue whale and humpbacks)  and odontocetes (meaning toothed whales) containing, dolphins, porpoises and other predatory whales such as the orca, beluga and sperm whales as well as beaked whales which are poorly misunderstood. 

The divergence between Mysticetes and Odontocetes was thought to have occurred around 30-40 million years ago. 

 

 

What is a pinniped? 

A pinniped is commonly defined as an animal that has front and rear flippers, spending most of its life cycle in the ocean but has the ability to come to land for extended periods of time. Therefore semi aquatic. Examples include seals, sea lions and walruses. Pinnipeds can be broken down into three distinct groups

What are the three groups of Pinnipeds? 

Odobenidae, often having upper canines known as tusks. A nearly extinct family whose only living member is the walrus.

Otariidae, meaning eared seals consisting of sea lions and furred seals. 

Phocidae, meaning you guessed it earless seal known as a true seal. 

 

 

What is a Sirenias?

Sirenias are commonly referred to as Sea cows. The unifying characteristics of Sirenians, being they are fully aquatic mammals that are herbivorous, they inhabit many biomes such as wetlands, swamps, rivers, estuaries and marine coastal waters. Sirenias consist of only 4 living species, these are split into 2 families. 

What are the Sirenias families?

Dugongidae (the Dugong) 

Trichechidae (Amazonian, West Indian and African Manatees), all their own species. 

What is a Fissiped? 

Fissipeds include Sea otters and polar bears, fissipeds are related to terrestrial carnivores like weasels and bears, while other fissipeds include Felidae (cats) and Canidae (dogs)

 

What is a Sea Otter?

Sea Otters are a marine mammal native to the North and Eastern coasts of the pacific ocean weighing between 14 and 45 kg they comfortably sit among the smallest of marine mammals, and the largest of the weasel family. Sea Otters have a lifespan of 15 - 20 years.  

 

 

What is a Polar Bear?

Native to the Arctic circle and nearby areas, giving them their name, the unmistakable white polar bear is closely related to the brown bear. Polar bears are the largest extant species of bears and land carnivores, weighing anywhere from 300 - 800 kg, considered the only marine mammal in the bear family for their dependence on the ocean for food and habitat. Polar bears' skin are in fact black, allowing them to absorb UV from the sun better in order to stay warmer.  

That's your comprehensive breakdown guide to marine mammals, from the large baleen whales to small Sea otters. Marine mammals consist of many shapes, sizes, groups and families with geographical dispersion in all corners of our planet. 

Thanks for taking the time to read Seacret’s guide to marine mammals. We hope this was educational and provided value, hopefully you learned something new. 

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