A lesson on how sharks and rays live underwater

ELASMO - My Life Underwater 

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Are all elasmobranchs torpedo-shaped like you, Elasmo?

NO! I have cousins called skates and rays. Imagine pulling my fins outward to be wings, and squashing my body flatter - then you have a skate or a ray! Great for finding food in the sand!

To be a good hunter, I have to be a good swimmer! I have a strong tail and fins to help me swim, but only forwards - I cannot swim backwards. The Shortfin Mako Shark is the fastest shark in the world. It can swim at 74 km per hour, and the shape of its tail helps it go that fast!

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Most fish are made of rigid bones. I'm an elasmobranch - my skeleton is made of cartilage, instead of bones. Cartilage is so flexible that I can touch my own tail!

Activity: Humans have cartilage in their ears. Hold your ears and give them a wiggle - they should be bendy, but very strong!

1 Fish 2 Shellfish 3 Carrion

Activity: Which foods would these teeth be good at eating?

Nosey - you can swim on the surface, but not breathe underwater. I will explain how sharks are better suited to life underwater than you are!

It's you who adapted to live OUTSIDE of water. If you saw my last adventure, you might remember that it was the ocean creatures that came first!

Boney fish have swim bladders full of air, just like a scuba diver's jacket.

Instead of air-filled swim bladders, elasmobranchs have oil in their liver to make them float in the water.

Boney fish have scales. Elasmobranchs have skin made of dermal denticles, tough teeth-like scales, that help them glide faster through the water, without friction.

I have special gel-filled sensors that can feel the electricity of an animal's heart, even when it's buried in the sand. These sensors are called AMPULLAE OF LORENZINI - they look like black dots on my snout and chin.

Elasmobranchs are like superheroes with x-ray vision - sensing creatures hiding in the sand

Hey Elasmo! My name is Nosey. How come you can live underwater, but me and my land friends can't? As much as we try, we can only stay down for a little while!

Tell me more!  How do you get oxygen from water?

All fish have gills. It may be easier to show you some pictures!

Boney fish have a pair of covered gills instead of lungs, but most sharks have 5 pairs of gill openings, and some even have 6 or 7!

I am a strong and agile APEX PREDATOR in the ocean. I have developed a whole set of adaptations to succeed as a hunter.

I have good eyesight and a wonderful sense of smell.

Activity: What other animals have adaptations that make it easier for them to feed?

Look at the gills in these elasmobranchs!

Activity: Can you count the gill slits on these elasmobranchs?

Activity: These elasmobranchs have spiracles, so they can suck water in and push it through their gills. Why would that be a good idea?

How do elasmobranches have babies? Do they have live young like giraffes, or do they lay eggs?

Some elasmobranchs lay eggs in small pouches called "eggcases" or "mermaid's purses", others have live young. Most elasmobranchs only have small numbers of young at a time.

This project was funded by the Erasmus+ project

The main reason we can breath under water is our gills. All fish have gills!&nbsp;

Watch the gills moving and taking oxygen from the water

ELASMO - My Life Underwater

No - we all have special teeth depending on the type of food we eat. Sharp, pointy teeth are good for fish-eating; flat teeth are good for crushing shellfish; and ones like bread knives are good for eating carrion (dead things)!

All sharks are fish, but not all fish are sharks!

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