Category: Other Marine Animals

10 Starfish (or Sea Star) Facts

10 facts, Other Marine Animals

starfish, sea star, orange starfish
Starfish/Sea Star photo from Wikimedia Commons by EsMynt

1. Starfish aren’t fish! They are echinoderms, invertebrates, and are related to sea urchins and sand dollars.

2. If an arm of a starfish becomes detached, it can grow a new one (though it might take up to a year to grow)!

3. To eat, a starfish spits out its stomach and digests whatever it’s eating (like a mussel or snail) on the outside of its body. Then it sucks back in its stomach to finish digesting.

4. There are 1,600 kinds of starfish in the ocean. They range in color from red, orange, brown (there’s a chocolate chip sea star), purple, yellow and more!

5. The tube feet of a starfish are amazing. They create suction by sucking in seawater. The tube feet help the sea star move, and manipulate its prey.

6. A starfish can live up to 35 years.

7. Starfish are eaten by other sea stars, fish, manta rays and sharks.

8. Not all starfish have 5 arms, some have up to 24 arms, like the sunflower sea star!

9. The crown-of-thorns starfish (COTS) is found in the Indo-Pacific and outbreaks of them cause damage to coral reefs. COTS eat exclusively coral polyps and cause the coral to turn white and die. The COTS cause almost as much damage as coral bleaching, like on the Great Barrier Reef off Australia.

10. Starfish have no brain, no blood and no central nervous system. They can “see” with eyes on the end of their arms. These eyes sense light and dark.

For more facts, visit Nat Geo Kids Starfish Facts
For more on the sunflower sea star, visit Monterey Bay Aquarium Animals A-Z

Ever wonder what kind of sea star Peach from Finding Nemo is? Visit The Real Fish of Finding Nemo

What are Horseshoe Crab Blood Uses?

Other Marine Animals, People and the Ocean
horseshoe crabs, horseshoe crab blood uses
Horseshoe Crabs mating on the beach (via Wikimedia Commons)

What are Horseshoe Crab Blood Uses and How Do They Spawn?

Spawning time!


Hi, I’m Edna, a horseshoe crab. I’m not truly a crab, but an arthropod related to scorpions, spiders and ticks. I’m excited because it is the new moon. It is time for me to mate and lay my eggs in the sand. This is a big deal to us horseshoe crabs to actually come out of the water for this special event.

It’s getting dark and the tide is high-I sense it’s time to crawl out of the water. I don’t have good vision, even though I have up to 10 eyes! Although I don’t see as well as humans, my vision is one million times better at night than in the day.

My special chemicals, or pheromones, that I release into the water attract male horseshoe crabs to me in the surf. One of them latches onto my back with a special claw. It’s almost time to lay my eggs!

I begin my climb out of the surf. Waves crash all around me until I make it to the wet sand. I climb out a little further and begin digging a hole to lay my 4,000 eggs. I dig and dig, and finally begin to deposit my eggs. The male horseshoe crab clasped to me fertilizes the eggs as they come out of me.
I finish laying my eggs in the sand, and the male detaches from me.

Where am I going?

Wait, why am I floating in the air? What happened to the sand and water? Something has grasped me. Am I doomed?


I am in a dark place. I scramble to crawl up the wall placed before me but it’s no use. My legs just keep scratching up against something, but I can’t crawl out or over it.

Lots of other horseshoe crabs are piled around me. I sense the moonlight one moment, and the next it is gone. I thought my life might end being eaten by a shark, but surrounded by my fellow horseshoe crabs in the dark?

Where am I?


I am tired after laying all those eggs, so I sleep. When I wake up I am in a bright area. It’s not the warm sun, but there is light all around. I can move all my legs, but I can’t go anywhere. I feel my blue blood being drained from me by a cord, and it’s not a good feeling.

Back home!

Soon enough I am lifted in the air and placed in the dark place again with all the other horseshoe crabs. After what feels like hours, I feel myself lifted into the air again. The warm sun is all around me. Then I am placed down on the wet sand. I’m home! I scurry into the surf and back into the water. What a night and day I’ve had!

Note: So what are horseshoe crab blood uses? Horseshoe crabs blue blood is harvested by the biomedical industry for testing of drugs and medical devices. Their blood is blue because they use copper as a carrier for oxygen, while humans use iron as a carrier of oxygen in their red blood. There are synthetic alternatives to LAL, but their use isn’t fully adopted yet.

It is unknown if all the biomedical industries actually return all the horseshoe crabs they bleed back into the wild as they may be sold for bait instead. There has been a study that horseshoe crabs that are bled and returned to the wild have altered behavior and the females have less spawning attempts.

The Atlantic Horseshoe Crab is “Near Threatened” to being endangered.

Check out these websites for more information:
Biomedical bleeding may impact horseshoe crabs spawning behavior and movement

More on horseshoe crab spawning and how to donate to help them!

And check out Plankton:The Real Monsters of the Ocean

10 Fabulous Sea Cucumber Facts

10 facts, Other Marine Animals
sea cucumber facts, sea cucumber species, sea cucumber
Chocolate Chip Sea Cucumber photo by: NOAA National Ocean Service

10 Sea Cucumber Facts

1. Sea cucumbers are not a vegetable, but an invertebrate (animal without a backbone). They are like a squishy leather-like terrestrial cucumber with a mouth on one end and an anus on the other. They breathe through their anus(!)

2. There are 1,200 known species of sea cucumbers. Sea cucumbers come in many colors, including orange, red, and brown.

3. Sea cucumbers are echinoderms and are related to sea urchins and sea stars.

4. They are abundant on coral reefs, one per square meter on un-fished reefs. Below 15,000 feet (the deep sea), they make up 90 percent of life on the seafloor.

5. Small animals sometimes take refuge in the sea cucumber’s rectum!

6. They average 3-12 inches long, but can be as small as 0.75 inches and as long as 6.5 feet.

7. Sea cucumbers are nocturnal and play an important role on a coral reef. *see more below

8. Sea cucumbers have 2 lines of defense. They can shoot out white sticky threads that tangle up any predator. They also can expel their internal organs, which are then regenerated.

9. The larvae (“baby” sea cucumbers) of sea cucumbers are planktonic and float in the ocean currents. The adults are benthic, which means they live on the seafloor.

And our last sea cucumber fact:
10. A sea cucumber can live 5-10 years (if it doesn’t get eaten or fished out as an Asian delicacy).

*Sea cucumbers are scavengers and ingest sand to eat whatever’s “stuck” to it, much like an earthworm ingesting dirt for food. The sand moves through the sea cucumber’s acidic digestive tract. The acid dissolves calcium carbonate from the sand and it is pooped out into the surrounding seawater. Corals use that calcium carbonate to build their skeletons. Calcium carbonate is alkaline (like an antacid) and can buffer acidic seawater. Scientists are studying if sea cucumbers can help mitigate the negative effects of ocean acidification due to climate change. For more on ocean acidification, see Ollie the Octopus and Ocean Acidification Definition
Facts from:
7 Facts You Didn’t Know About Sea Cucumbers
National Geographic page on Sea Cucumbers
National Wildlife Federation’s Page on Sea Cucumbers

What Is Bioluminescence and Why Do So Many Deep-Sea Animals Have It?

Fish, Other Marine Animals
bioluminescence, bioluminescent ocean waves, bioluminescent waves, bioluminescent plankton
Bioluminescent ocean waves Photo credit: Phil Gibbs on Visualhunt.com / CC BY-NC-ND

What is bioluminescence?


Bio = biological, or life, Lumen = light (unit)
Bioluminescence is the biochemical emission of light by living organisms such as deep-sea fishes. It produces the “glow-in-the-dark” look of certain animals such as fireflies and the “fireworks” show when plankton are disturbed in the ocean(see photo of bioluminescent ocean waves).

What percentage of animals in the deep-sea are bioluminescent?


90% of animals in the deep-sea (below 1,640 feet or 500 meters) are bioluminescent (according to NOAA [National Oceanic and Atmospheric Administration]).

How do animals and plants produce bioluminescence?


Two chemicals are mixed together with oxygen and the reaction produces light. The chemicals are luciferin and luciferase and together they produce oxyluciferan.

Bioluminescence is made up of what colors?


Mainly blue-green as red is absorbed the further you go down in the ocean. There are species that emit infrared and red light and one group of organisms that produce yellow light.
from Causes of Color website

What kinds of ocean animals are bioluminescent?


Bioluminescent ocean organisms include bacteria, jellyfish, starfish, clams, worms, crustaceans, squid, fish, sharks and more to be discovered! (list according to NOAA)

Why are animals bioluminescent?


Animals are bioluminescent for protection as the light will scare some predators away. The vampire squid has bioluminescent mucus that they eject (like ink) towards predators. Animals can use bioluminescence to find mates (which is hard when in the dark, deep sea with no other light). They also can use it to find food (like Dory in Finding Nemo being drawn to the anglerfish lure. Fortunately Dory wasn’t eaten!). Also it can be used in communication, and for illumination.

What questions do you have about bioluminescence? Leave a comment below.

Prochlorococcus (Blue-Green Bacteria) are the Earth’s Most Abundant Photosynthesizing Biomass

Other Marine Animals
Prochlorococcus, Prochlorococcus marinus
Prochlorococcus is the most plentiful photosynthesizing biomass on Earth Photo by: Anne Thompson, Chisholm Lab, MIT

That’s right, a bacterium called Prochlorococcus marinus, is the most plentiful photosynthesizing biomass on Earth.

There are a billion billion billion (or trillion trillion) Prochlorococci in all the world’s oceans. They’re not a plant (though they have chlorophyll like plants). They’re definitely not terrestrial.

Prochlorococcus is so small that you could lay 100 of them end-to-end and they would be the width of a human hair!

This important organism was first described by scientists in 1992.

Prochlorococcus is very important to the Earth’s ecosystem. It makes up the base of the food chain in the oceans.

They may account for 20% of the global production of oxygen (1 out of every 5 breaths you take are from Prochlorococci), and they take up to 25% of the carbon dioxide from the atmosphere.

Prochlorococcus is the smallest of the photosynthetic organisms on Earth. It is also “possibly (the) most plentiful genus on Earth,” meaning that there are more Procholorococci than any other organism on Earth.

Photosynthesis is when organisms with chlorophyll (green pigments) take the sun’s energy and produce food for themselves. Usually you think of plants photosynthesizing, but in this case it’s bacteria. In the process oxygen is released as a waste product. In the case of the ocean, oxygen is released from a water molecule.

Procholorococci live in subtropical waters (between 40 degrees N and 40 degrees S) that are nutrient poor (called oligotrophic). They are mainly found in the sunlit surface waters (euphotic zone) of the ocean, which goes down to 656 feet (200 m).

Procholorococci have been around for 3.5 billion years!

Not bad for an organism you probably never heard of until today!

For more information on Procholorococcus visit these websites:

Encyclopedia of Life article on Procholorococcus

PBS article on “Without These Ancient Cells, You Wouldn’t Be Here”

Also see “Krill: The Most Abundant Animal on Earth”

European Eel Life Cycle

Other Marine Animals
European eel by: Felice Supino, Wikimedia Commons
European eel by: Felice Supino, Wikimedia Commons

Hi, I’m a European eel. I was born in the Sargasso Sea. The Sargasso Sea is located in the North Atlantic Ocean, due east of Bermuda. I use the Earth’s magnetic field to navigate, a sixth sense of sorts. When I swim, I sense subtle differences in the Earth’s electromagnetic field so I can sense where I am as a youngster and find the Gulf Stream and other currents. This way I can use the currents to hitch a ride to the west coast of Europe and North Africa.

Eel Life Cycle by: Salvor Gissuradottir, Wikimedia Commons
Eel Life Cycle by: Salvor Gissuradottir, Wikimedia Commons

As a youngster (leptocephali) I’m part of the plankton, the small plants and animals that make up the bottom of the food chain in the ocean. After 7-11 months (up to 3 years) I will become a glass eel. Then I will enter freshwater (or brackish, a combination of salty and freshwater) rivers and become an elver. Then as a yellow eel I will mature into an adult. I’ll spend 6-20 years here. Then I become a silver eel that will make the long journey of 3,107-3728 miles (5,000-6,000 km) back to the Sargasso Sea to breed.

In freshwater streams, yellow eels will eat invertebrates such as mollusks, crustaceans, and even slugs and worms from land! The yellow eels also eat fish, which they can scavenge.

Eels have been kept for 85-115 years in aquariums! Scientists estimate eels average 10-20 years in the wild.

Eels’ blood is poisonous, but their poison is killed by cooking.

American eels are also born in the Sargasso Sea, but they ride the currents to the east coast of North America.

Coral Reef Bleaching and The Great Barrier Reef

Other Marine Animals, People and the Ocean
coral reefs of Great Barrier Reef, coral reef bleaching
Photo credit: FarbenfroheWunderwelt via Visual Hunt / CC BY-ND

Why are the corals on the Great Barrier Reef off of Australia bleaching? Why is coral reef bleaching important?

First a little background on corals.

Hi, I’m Polly, a coral polyp. The animal you think of as “coral” is actually made up of lots of little coral polyps. We use calcium carbonate to make our skeleton and many of us together make the base of a coral reef.

We’re only millimeters wide (0.1 inch) and centimeters deep (1.2 inches) with tentacles sticking out. We use our tentacles to find food floating in the water.

But our main source of food is made for us by our friends inside us, the zooanthellae. These are our photosynthetic symbionts. In other words, the plants inside of us use sunlight to make the food that we eat. These zooanthellae are important to us, but when exposed to stressors like increased heat or acidity, they often expel themselves from us. This causes coral reef bleaching.

Coral reef bleaching can be caused by the ocean warming due to climate change. The ocean absorbs 90 percent of the heat in the atmosphere caused by human activities. Coral bleaching can also be affected by ocean acidification. The ocean becomes more acidic (like soda or stomach acid) when it absorbs carbon dioxide from the atmosphere. There is also pollution of all sorts, including plastic, chemical, and sediments that can also cause the coral reef to bleach.

A recent scientific study found that “huge portions” of the northern end of the Great Barrier Reef died last year (2016) due to warming seawater. Just an increase of two or three degrees Fahrenheit (1.2-1.6 degrees Celsius) can cause coral reef bleaching. The southern end of the Great Barrier Reef is bleaching as we speak.

So why do we need coral reefs? Coral reefs house twenty-five percent of all marine life in the oceans.
One billion people rely on the ocean for their primary source of protein, and many of those in developing countries rely upon coral reefs for it.

So what can you do? Here are some excerpts from the Nature Conservancy’s 10 Easy Steps to Protect Coral Reefs

1. Support businesses such as fishing, boating, hotel, aquarium, dive or snorkeling operators that protect coral reefs.
2. Practice safe snorkeling and diving practices such as not touching the coral and not anchoring on coral.
3. Volunteer on vacation to clean-up a coral reef or help plant one.
4. Plant a tree to reduce the carbon dioxide in the atmosphere.
5. Dispose of your trash (or recycle!) properly, especially near the ocean. Better yet, join a beach clean-up.

Also see Ollie the Octopus on Coral Bleaching and the Great Barrier Reef

Meet Cooper the Copepod & Learn About Microplastics

Other Marine Animals
copepods & microplastics
Meet Cooper the Copepod to learn more about microplastics photo by Uwe Kils Wikimedia Commons

Hi! I’m Cooper the Copepod. What is a Copepod? Well, I am a tiny animal that is part of the plankton. Plankton are the microscopic plants and animals that make up the base of the food chain in the ocean. I have a teardrop-shaped body and long curved antennae.

I am the fastest and strongest jumper on the planet, even faster than jumping land animals like kangaroos! But while I am only 1-2 millimeters long, I reach speeds of 2-4 miles per hour (3-6.4 km/hr) while jumping. The equivalent in a human would be a 5 foot 8 inch person going a whopping 3,800 mph while jumping! (livescience’s article flea-sized creatures are the fastest jumpers)

I’m here today not to impress you with my stats, but to talk to you about garbage in our oceans, specifically microplastics. Plastic pollution in our oceans is a big deal. 8 million tons of plastic are dumped into our oceans each year. You may have heard of the Great Pacific Garbage Patch in the Pacific Ocean, one of many garbage patches in our oceans. They are mainly made up of plastic waste such as soda bottles, bottlecaps, plastic flatware, plastic grocery bags, and discarded plastic fishing nets.

But more important and insidious are the microplastics. These plastic particles are less than 5 mm in size. They include microbeads from beauty products (like exfoliants for your skin), microfibers from washing synthetic clothing (polyester and nylon microfibers are not caught by lint traps nor at the filters in sewage treatment plants) and plastic fragments worn down from larger plastic products.

To tiny critters like me, the microplastic looks good enough to eat, and we do that when come across it. Animals larger than us such as fish eat us, and so on up the food chain until we get to predators such as sharks, tuna, sea turtles and humans. Did you know you contain several pounds of plastic in your body?

Up to 8 trillion microbeads enter the waterways of the United States everyday (CNN Obama bans microbeads). But fortunately in December 2015 the U.S. outlawed the use of microbeads in health and beauty products by 2017!

There is still the matter of other micro and macro plastics in the ocean—the best way to take care of them is to reduce the amount of plastic now entering our oceans. For the sake of me and my neighbors, please recycle plastics! Also take part in beach cleanups or even just clean up in your neighborhood—as Gill said in Finding Nemo, “All drains lead to the ocean, kid.”

10 Lion’s Mane Jellyfish Facts: the Biggest Jellyfish

10 facts, Other Marine Animals
Lion's Mane Jellyfish facts
Lion's Mane Jellyfish photo by: NOAA

10 Lion’s Mane Jellyfish Facts: the Biggest Jellyfish

1. The Lion’s Mane Jellyfish is the biggest Jellyfish in the world. Its bell can reach up to 8 feet in diameter, and its tentacles up to 120 feet long (that’s longer than a blue whale!).

2. The Lion’s Mane Jelly lives in the North Atlantic, North Pacific, and Arctic Oceans.

3. The Lion’s Mane Jelly is bioluminescent (glows in the dark!).

4. Like all jellies, the Lion’s Mane Jelly has no brain, blood, or nervous system.

5. Like all jellies, the Lion’s Mane Jelly is 95% water.

6. There are 200 species of True Jellies.

7. All Jellies are radially symmetrical.

8. Jellies have no eyes, but rather eye spots that detect light and dark.

9. Lion’s Mane Jellies have nematocysts in their tentacles that they use to sting their prey. Nematocysts are barbs (sharp points) filled with venom.

10. A Jelly can sting you even if washed up on the beach so be careful! Jelly stings on humans can be treated with vinegar to lessen the pain.

Also see: 10 Jellyfish Facts for Kids
Why Jellyfish may become the “Cockroaches of the Sea”
Lion’s Mane Jellyfish from Oceana

10 Sea Sponges Facts You Didn’t Know About

Other Marine Animals

Blue Vase Sponge photo by: Cherilyn Chin
blue vase sponge, sea sponges facts

10 Sea Sponges Facts You Didn’t Know About

1. Sea Sponges are animals, not plants.

2. Sea Sponges have been in the ocean for 500 million years.

3. Sea Sponges don’t move, but they filter lots of water for food (plankton) and oxygen.

4. Sea Sponges are among the most simple of multi-cellular organisms.

5. There are about 5,000 species of sea sponges worldwide.

6. Some sponges are found in freshwater lakes and rivers.

7. The smallest sea sponges are 1 inch long (3 cm) (or flat against a rock), the largest over 4 feet tall (1 m).

8. Sponges do not have heads, eyes, brains, arms, legs, ears, muscles, nerves or organs!

9. Sea Sponges have pores that filter water in for food and oxygen, and pores that push out waste.

And the last sea sponges fact is:
10. Sea Sponges have few predators other than sea turtles, and fish because some produce toxins.

For more information see: Sea Sponges: Pharmacies of the Sea from the Smithsonian

Also see: 10 Fabulous Sea Cucumber Facts