How Much Do You Know About These Common Marine Animals?


Which male sea animal gives birth to its young?

The male seahorse gives birth to its young. It's one of only a few animals that does this.

Who has one of the loudest calls on Earth, at 188 decibels?

The enormous blue whale has one of the loudest calls on Earth. It can reach 188 decibels.

True or False: Dolphins sleep with one eye open.

It's true that dolphins sleep with one eye open to watch for predators. Their brains only turn off 50% when they sleep.

The heart of a blue whale is about the size of ______.

The heart of a blue whale is just about the size of a small car. The aorta is so large that a child could crawl through.

Which of these is a mammal?

These are all examples of sea mammals. The list includes seals, whales, sea lions, dolphins, otters, porpoises, walruses and manatees.

What do you call a group of jellyfish?

A group of jellyfish is called a smack of jellyfish. Did you know that they're older than dinosaurs and sharks?

A blue whale can grow up to _______ in length.

Remarkably, the blue whale can grow up to three Greyhound buses in length. It tongue alone can weigh as much as an elephant.

Which sea creature has three hearts?

An octopus has three hearts. Not only that, but it also has blue blood.

True or False: A sea sponge is a non-living creature.

Sea sponges are totally alive. However, they don't have a head, mouth, eyes, bones, lungs, brain or even a heart.

Dolphins can hear sounds up to _____ miles away.

Dolphins can hear sounds up to 15 miles away. They have a remarkable way of communicating with one another.

True or False: Some fish are poisonous.

Not only are some fish poisonous, but some are downright terrifying. Here's a list of fish that freak us out: The dragonfish, frilled shark, vampire squid, big red jellyfish, giant squid, coffinfish, anglerfish, snaggletooth and the blue ringed octopus.

What percentage of the living space on our planet is in the ocean by volume?

Would you believe that 99% of the living space on our planet is in the ocean? Just think of all that space!

The blue whale is the ________ animal to have ever lived.

The blue whale is the largest creature to have ever lived on this planet. That includes both sea and land.

How many miles can a green turtle migrate to lay its eggs?

A green turtle can migrate more than 1,400 miles to lay its eggs. It's like moving to a different state that has a better school system.

What do you call a group of herring?

A group of herring is called an army. That sounds pretty fierce, doesn't it?

How many lightbulbs could an electric eel power?

One electric eel could power 10 lightbulbs with its electricity. That's pretty powerful!

Which of these is true?

Fish are pretty flexible when it comes to gender! Some will change gender during the course of their lives, while others are both male and female.

Bluefin tuna are among the _____ fish.

Not only are bluefin tuna among the largest and fastest fish, they're also the most prized. Individual bluefins can bring as much as $20,000 at U.S. docks.

How fast can a penguin go underwater?

A gentoo penguin can swim underwater at up to 22 mph. In fact, they don't swim, but rather "fly" under the water.

How many species are in the ocean?

There are over 230,000 known species in the ocean. That being said, only about 5% of the ocean has been explored.

Sea coral is similar to what?

Sea coral is similar to human bone. Because of this, coral has been used for bone grafts.

Water animals are _____.

Water animals can be either vertebrates or invertebrates. That means that they are with or without a backbone

Marine animals live in ______.

Marine animals exclusively live in salt water. Freshwater animals are called just that.

True or False: Sea turtles have been on Earth longer than 220 million years.

it's true that sea turtles have been on Earth for longer than 220 million years. They have lived through many climate changes.

When did life begin in the ocean?

Ocean life has been around for over 3 billion years. Life on land has been around for 400 million years. You do the math.

Octopuses are ______.

Research is showing that octopuses are the most intelligent of the invertebrate creatures. They're also said to be sentient creatures.

How many blue whales are still on the planet?

There are only about 25,000 blue whales left on the planet. That means that they're an endangered species.

Dolphins are the only mammals that are born ______.

Dolphins are the only mammals that are born tail first. They are some of the most beautiful, intelligent and friendly water animals that we know.

How many kinds of fish can conduct electricity?

There are roughly 500 fish which can conduct electricity. The electric eel is so powerful that it could knock down a horse.

What is the largest predator in the ocean?

The great white is the largest predator in the ocean. Sharks attack people, but they don't eat them because there isn't enough fat.

Piranhas are known for their ______.

Piranhas are known for their powerful jaws and sharp teeth. They are omnivorous as well as cannibals.

Cuttlefish are famous for their ______.

Funny enough, cuttlefish emit water from their mantle to propel themselves! They also emit ink to ward off predators.

How long can a walrus stay underwater?

The walrus, a mammal, can stay underwater for up to 30 minutes. Those are some pretty powerful lungs!

Which sea animal is vegetarian?

The dugong, or sea cow, is one of the few vegetarian aquatic mammals. They consume about 88 pounds of sea grass every day.

Where is the heart of a shrimp located?

The heart of a shrimp is actually located in its head. Talk about head and heart becoming one!

Explore More Quizzes

Image: Shutterstock

About This Quiz

The oceans of the world are so vast that humans have only begun to explore the depths. In fact, many marine scientists believe that there are thousands, if not millions, of currently unknown sea creatures waiting to be discovered. But what about the ones we know of? They are a remarkable and diverse array of animals - some are curiously similar to land dwellers and others couldn't be more different. How much do you think you know about marine creatures? Now is the time to answer the question. 

Do you know the male marine animal who gives birth? Or how large the heart of a blue whale is? Hint: it can carry you and three of your best friends inside. Do you know what a group of jellyfish is called? If you don't, you will smack yourself when you find out.

Dolphins are one of the most beloved sea creatures and have uniquely come to the rescue of humans time and again, perhaps because they are excellent at hearing sounds of distress. Do you know how far they can hear while swimming?

Sea creatures big and small are some of the most fantastic creatures in the world, but how much do you think you know about them? This quiz will probably tell you - not enough. Take this quiz to find out if you will sink or swim. 

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!