under the sea

Pop on your scuba gear, we're going on an underwater adventure! First up, some fascinating facts about the many different creatures that you can find in our oceans. From jellyfish to seahorses, whales to pufferfish join us as we discover more about this incredible sea life! 

 

 

Blue Tang

You may recognise this fish as Dory…but do you know its name? This is the Blue Tang – a small fish native to coral reefs in the Indo-Pacific ocean and can grow up to 30cm (the same size as an average ruler!).

Known for its noticeable colour patterns, blue tangs don’t always begin their life as this vibrant shade of blue. Young blue tangs are a bright yellow! And as they get older they can flush into deeper blues and shades of violet.

And whilst these colourful creatures may look harmless, they actually have razor-sharp, venomous spines that stick out on either side of their tails when they are in danger.

Blue tangs love clear waters and surrounding coral reefs and their favourite meal is algae which they scrape off the reef with their little sharp teeth!

Crab

There are over 6,700 species of crab? That’s so many! These include Japanese Spider Crabs, Pea Crabs, Snow Crabs, King Crabs and Blue Crabs. Can you name any other crab species?

Even though crabs live in the sea, they’re not fish, they are crustaceans! You can tell a crustacean from their hard outer shell which protects them from predators. Crabs have lots of legs…10 to be exact! This means they are decapods and using all these legs, they can walk in all directions! But you’ll usually see them scuttling sideways.

You can find crabs in just about any body of water! They reside in salt and freshwater both warm and cold and they don’t mind if it’s deep or shallow…they’re not picky! Crabs can swim but they tend to stay closer to the sea floor so they can happily scurry around.

Can you guess how crabs communicate? They use their claws and communicate by drumming or waving them!

 

Great White Shark

You’ll recognise these ginormous sea creatures with their white underbelly and lots of sharp teeth… that’s right it’s the Great White Shark! The cool water dwellers are the largest predatory fish on our planet measuring at around 4.6m long (up to 21ft).

And they’re super swimmers too – these streamline sharks have perfected their tail technique which helps propel them through the water at nearly 40 miles per hour (that’s 60km per hour!).

Great white sharks are usually on the hunt for sea mammals such as sea lions, seals and small whales and these big eaters need lots of sharp teeth for chewing. Luckily, they are equipped with a set of 300 sharp, triangular teeth arranged over seven rows…wow!

Did you know that a great white has an incredible sense of smell? They can detect a colony of seals two miles away! If there was only one drop of blood in 100 litres of water, a great white would smell it. Now that is seriously impressive! 

Humpback Whale

These singing powerful swimmers are a marine marvel – the mighty Humpback Whale! Weighing in at over 40 tons, these enormous creatures are known for their incredible swimming technique. Their tail fin (also called a fluke) is used to propel them through the water and occasionally out of it. We still don’t know if this ‘breach’ of the water serves a purpose or if Humpbacks just do it for fun – but we hope it’s the latter!

Did we mention singing? Yes, we did! Humpback whales are known for their magical singing which travels great distances through the ocean. These are a combination of moans, cries, howls and other complex noises that sometimes last up to 30 minutes long! Scientists believe that this melody of songs is so that humpback wcan communicate with each other – just like humans talking.

As if they’re not already lovely enough, these massive mammals have their own gesture of affection towards their young. Mother and their calves (baby whales are called calves) swim close together, often touching their flippers – almost like they’re holding hands. So cute!

When the winter comes, humpback whales migrate from chilly feeding grounds near the poles to warmer breeding water which is closer to the equator, and they make this journey annually.

 

 

 

Jellyfish

The magical jellyfish can be found across the world and has been around for millions of years – even before dinosaurs roamed the Earth! They like cold and warm water, deep or shallow and can be found along coastlines as well.

There are many different colours of jellyfish that can be found, this interesting creature can sometimes be clear or a vibrant pink, yellow or blue. And there are some jellyfish that can be bioluminescent, which means they produce their own light!

Did you know that jellyfish are 95% water? Jellyfish are invertebrates, they are made up of a smooth bag-like body and tentacles. They have no heart, brain, eyes or bones! And these wiggly wonders use their tentacles to stun prey before eating it.

Pufferfish

Do you know where pufferfish live? They prefer subtropical and tropical marine waters, including coral reefs but some species of pufferfish live in brackish and even fresh water. There are over 120 species of pufferfish, also known as blowfish, worldwide!

We think these little fish are quite cute – but they are most definitely deadly! Most pufferfish contain a toxic substance that makes them deadly to humans and some fish. When frightened or in danger, these clumsy swimmers fill their stomachs with lots of water and blow themselves up to several times their normal size. Some pufferfish wear wild colours and markings to advertise their toxicity while others are more muted to blend in with their surroundings.

Can you guess what a pufferfish eats? Invertebrates and algae are the meal of choice for most pufferfish but they also have little hard beaks and use these to crack open mussels, clams and other shellfish!

Seahorse

There are over 40 species of these tiny fish and can you guess how they got their name? That’s right - because the shape of their head looks like a tiny horse head! You can find seahorses in tropical and temperate coastal waters where they bob along upright amount seaweed and plants.

You may have seen pictures of a seahorse gripping onto vegetation – this is because they have a very flexible, curled tail that means they can anchor themselves to plants. Isn’t that cool?!

And seahorses have a very interesting way of swimming…they move their back fin to go forward and if they need to go up or down, they adjust the amount of air in a tiny pocket called a ‘swim bladder’ that is on the inside of their bodies.

Just when you thought a seahorse couldn’t be any cuter, did you know that when baby seahorses are born, they are only the size of an M&M and to stay safe they cling together in small groups, gripping on using their tails!

Giant squid

An almost mystical creature, the giant squid is one very hard-to-find creature! There’s only a limited about we know about these enormous invertebrates as they inhabit and inhospitable depth in the ocean, making them hard to study.

The largest giant squid recorded so far was measured at almost 18m long (59ft) and weighed nearly a ton. As they live so deep down, it is quite dark and difficult to see! To help them see way down there, they have ginormous eyes – measuring about 25.5cm (10 inches) in diameter. The biggest eyes in the animal kingdom!

Probably feasting on a diet of fish, shrimp and other small squid these creatures have long tentacles that help them bring their food into their beaklike mouths. Like other species of squid, they have eight legs and use the water to propel themselves along – drawing water into their body and then forcing it back out is how they get moving!

Bonus facts!

Did you know that the ocean can be split into layers and zones? Let's go through each one! 

 

Zone 1 – the epipelagic-zone (aka. the sunlit zone): this is the upper zone of the ocean, ranging from the surface to approximately 200 metres deep. The main notable factor in this layer of the ocean is the presence of sunlight which allows for photosynthesis to occur in plants, algae, and other organisms such as phytoplankton, which makes up the basis of the ocean food chain.

Due to the presence of light and warmer sea temperatures, it is no surprise that around 90% of the ocean’s creatures reside primarily in the epipelagic zone, including favourites like dolphins, tuna, jellyfish, sea turtles, seals and stingrays.

Zone 2 – the mesopelagic-zone: this area of the ocean ranges from approximately 200-1000 metres deep and is also known as the ‘twilight zone’ due to the dim conditions. Due to this low light level, plants are unable to grow. This area is home to many species of fish that are usually small and often luminous, for example, the lantern fish! Large animals from the epipelagic zone, for example, tuna and blue whales, often dive to this layer of the ocean to feed.

Other creatures, for example the sperm whale, prefer to live primarily in this zone, and often dive deeper into zone 3 for their food…

Zone 3 – the bathypelagic-zone (aka. the midnight zone): spanning from 1000-4000 metres deep, this area of the ocean is completely void of sunlight, existing in complete darkness. This zone is home to some more strange looking creatures, including the famous blobfish. It is also home to the reason why sperm whales descend to this zone – the giant squid!

Zone 4 – the abyssopelagic-zone: this zone, known commonly as ‘the abyss’, extends from 4000-6000, reaching the seafloor. Due to cold temperatures of around 2 degrees Celsius and the extreme pressure (up to 11,000 pounds per square inch!), few organisms can survive in this hostile zone. As a result, creatures that do live in this zone have some very interesting adaptations, such as hinged jaws that drag along the floor to catch food, or bioluminescence, used to attract prey!

Zone 5 - the hadalpelagic-zone (aka. the trenches): the zone refers to areas of the ocean deeper than 6000 metres, in deep sea trenches. These are deep indents in the sea floor that result from tectonic activity and reach depths up to 10,935 meters (remember the Mariana Trench?). Very few creatures reside in these zones, including bacteria, small isopods, and invertebrates such as sea cucumbers!