When young children think about where fish reside, they often exclaim, “In water!” Indeed, fish inhabit various water bodies, including lakes, rivers, oceans, and even small bowls in our homes. Similarly, whales also dwell in water, leading to the question: are whales fish? In this article, we will explore the resemblances and distinctions between whales and fish, shedding light on their unique characteristics in an engaging, friendly manner.
Where do Whales and Fish Reside?
Whales and fish share a common habitat: the aquatic environment. Fish inhabit both freshwater and saltwater, while whales predominantly reside in the ocean. Interestingly, a few freshwater dolphin species, such as the Amazon River dolphin, also inhabit freshwater areas. Unlike some animals like alligators and crocodiles that dwell on land and water, whales and fish are exclusively aquatic creatures.
How Whales and Fish Breathe
Whales, being aquatic mammals, breathe air through their lungs. They come to the water surface to inhale oxygen using their blowhole(s), which are directly connected to their lungs. The capacity of the lungs in large whales, like sperm whales, grants them the ability to hold their breath for up to 90 minutes!
On the other hand, fish possess gills, which are essential for extracting oxygen from water to sustain their lives. Gills are slits on the fish’s body that allow water to pass through, extracting oxygen from the water and eliminating carbon dioxide. Some fish can obtain sufficient oxygen from water without swimming, while others, like certain sharks, need to keep moving to maintain a steady flow of water across their gills. Some species even possess a buccal pump system, which actively pulls water into their mouths and over their gills, eliminating the need for constant movement.
Both whales and fish have developed unique ways to find and consume their prey. Whales and dolphins use echolocation to locate krill and other food sources in the deep ocean. Fish, such as the giant squid, rely on their keen sense of sight and specialized organs for capturing and consuming their prey. Each aquatic species has its distinctive method of respiration and foraging, designed to adapt to their respective habitats.
Fish vs. Whale: Comparing Their Sizes
Swimming Techniques
Whales hold the title for the largest animals on Earth, with the blue whale reaching lengths of 70-90 feet, and even up to 110 feet in some cases! Other massive whales include the fin, right, sperm, and humpback whales. However, some fish species can also grow to impressive sizes. The whale shark, for instance, can grow to over 50 feet in length. Other large fish include the basking, great white, and tiger sharks.
The giant oceanic manta ray is the largest ray (a type of fish), and the ocean sunfish holds the title for the largest bony fish (Osteichthyes). The ocean sunfish has a peculiar appearance, with no tail and a blob-like shape. It can reach 14 feet from fin tip to fin tip and weigh up to 5,000 pounds – comparable to an adult rhino!
When it comes to swimming, whales and fish have different techniques. While whale tails are horizontal with fins that move up and down, fish tails are vertical, moving back and forth for propulsion. Some fish, like rays, don’t even rely on their tails for swimming; instead, they flap their sides to create a current to glide through the water.
How do Fish and Whales Maintain Their Temperature?
Whales, as mammals, are warm-blooded creatures. They maintain their body temperature with a thick layer of blubber that insulates and keeps them warm, even in cold ocean temperatures. Dolphins, despite appearing sleek and slim, also possess a layer of blubber beneath their skin for the same purpose.
On the other hand, fish are cold-blooded, which means they can adapt to the temperature of their surroundings and do not need to retain warmth like mammals. However, there are exceptions in the fish world. Some tuna and sharks are partially warm-blooded. Interestingly, in 2015, scientists discovered the opal fish, the first fully warm-blooded fish. These large, round fish shimmer in sunlight and inhabit areas off the coast of Hawaii. Research showed that their core temperature remains consistently warm as heat circulates throughout their entire body.
The diet of whales and fish also plays a role in their temperature regulation. Filter-feeding whales, for instance, consume large amounts of food from their food sources, which contributes to their energy budget and helps maintain their body heat. Similarly, fish acquire calories and heat from their metabolism according to their specific diets.
How do Whales and Fish Reproduce?
Whales, being mammals, give birth to live offspring. Their babies are quite massive; a newborn blue whale can weigh between 5,000-6,000 lbs, equivalent to an adult rhino. Generally, whales have one baby at a time, with rare occurrences of twins.
In contrast, fish reproduce by laying eggs, often in large quantities. Some fish species can lay over a thousand eggs at once. The most common method involves females releasing the eggs into the water or near rocks and crevices, after which males fertilize them. The eggs then develop into larvae, eventually maturing into adult fish. However, some fish carry eggs within their bodies, releasing live larvae upon hatching.
Sharks present a more complex case, as their reproduction methods vary. Some sharks lay eggs (oviparous), while others give birth to live baby sharks (viviparous). Although sharks do not lay thousands of eggs like fish, they have more offspring at once than whales. For instance, a sand tiger shark typically gives birth to two babies, while a blue shark can give birth to over a hundred live shark babies, resulting in many siblings at once.
So, are whales fish?
Whales, though often referred to as ocean giants, are not considered fish. These marine mammals have significant differences from fish. For example, whales are warm-blooded, while most fish are cold-blooded creatures. Whales also respire using lungs, taking in air from above the water’s surface, while fish extract oxygen underwater through gills. In terms of reproduction, whales give birth to live offspring, whereas most fish lay eggs.
Whales evolved from land creatures about 50 million years ago. Biologically, they belong to the family of toothed whales, while fish have remained adapted to their aquatic environments throughout the fossil record. The relationship between these marine giants conveys one of the wonders of biology and evolution.
How do whales and fish raise their young?
Whales, being mammals, usually nurture and care for their young. Newborn whales depend on their mothers for milk, which also helps to strengthen their bond. Some whale calves stay with their mothers for a period ranging from 6 months to several years.
In contrast, fish generally do not provide parental care upon hatching. Many fish species hatch with a nutrient sac, helping them survive until they can find food independently. Shark offspring, particularly those born from eggs, are usually ready to survive on their own after hatching. For live-born sharks like the hammerhead, the mother tries to find a suitable location to give birth, ensuring the young have access to food and shelter. However, these young sharks are born prepared to set out on their own.
Whales often migrate during their life cycle, which can impact how they raise their young. For example, some species travel long distances to specific breeding and calving grounds before returning to their feeding areas with their calves in tow.