Category: Other Marine Animals

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 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.