Category: 10 facts

10 Cool Shark Facts: Your Questions Answered!

10 facts, Elasmobranchs, Sharks, sharks
bull shark bahamas, bull shark, bahamas
Bull Shark By Albert Kok~enwiki – Own work, CC BY-SA 4.0

The following are 10 Cool Shark Facts in a question and answer format.

1.How many shark species are there?

There are 512 described and 23 un-described shark species (according to Wikipedia)

2. Are sharks vertebrates?

Yes, sharks are vertebrates. Vertebrates have a backbone or spinal column. In the case of sharks, they have a spinal column made out of cartilage, not bone as in other vertebrates like bony fishes.

2.What is a group of sharks called?

A shoal (this applies to other fish as well)

3. What are baby sharks called?
Pups!

5. Are sharks endangered?
At least 143 species are on the IUCN red list with 210 more as data deficient (meaning we haven’t studied them closely enough to know how endangered the sharks are). But all sharks are in danger of becoming endangered due to overfishing, pollution, and other threats facing our oceans.

6. How many millions of years old are sharks?
The first sharks appeared 440 million years ago.

7. Which shark is the smallest? Which shark is the largest?
The smallest shark is the dwarf lantern shark, which grows to 7.9 inches (20 cm)
The largest shark is the whale shark, which can grow up to 60 feet (but is found to be 18-33 feet long on average)

8. Are sharks found in freshwater or saltwater?
Most sharks are found in the ocean in saltwater, but the river sharks are found in fresh and brackish water (slightly salty water) in Asia and Australia. The bull shark is unique in that it can live both in fresh and saltwater in tropical rivers worldwide.

9. Do sharks have swim bladders?
No, unlike the bony fishes, sharks don’t have swim bladders but the oil in their livers help them stay afloat.

And the final cool shark fact is:
10. How often do sharks eat?
It varies greatly between shark species. A great white shark can go a month without food after a full meal.

Also see: 10 Not-so-Scary Tiger Shark Facts

10 Interesting Great White Shark Facts

and Great White Shark’s Adventure at the Monterey Bay Aquarium

Fun quiz on sharks from NatGeoKids

The diversity of shark sizes graphic

Sharks on endangered species list

List of all sharks on Wikipedia

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

10 Fun Facts About Opah Fish, or Moonfish

10 facts, Fish
Opah fish, Moonfish, opah fish facts, opah fun facts
Opah fish or Moonfish photo by: NOAA Fisheries

1. The opah, or moonfish, is a fully warm-blooded, deep-diving flat and round fish.

2. The opah has a silvery gray body, red fins and mouth, and white spots all over.

3. Opah average 100 pounds (but can weigh up to 200 pounds) and is the size of an automobile tire-about 3 feet in diameter-but oval shaped.

4. Scientists have discovered recently through DNA testing that there are 5 distinct species of opah.

5. Opah eat fish, krill and squid.

6. Opah dive to depths of 165-1300 feet (50-400 meters).

7. Opah swim using their pectoral (side) fins and swim quickly like tuna.

8. Predators of opah include humans and large sharks such as great white sharks and mako sharks.

9. Scientists have tagged opah and found that they migrate thousands of kilometers.

10. Opah are caught as by-catch—by accident—by the tuna and swordfish fisheries. Off the United States, 30,000 opah were caught by the Hawaiian longline fishery in 2015 and the fishery is worth 3.2 million US dollars.

Also see a similar looking fish, the Mola Mola or Ocean Sunfish: 10 Interesting Facts About the Mola Mola or Ocean Sunfish

Articles used:
Opah, the first warm blooded fish identified: 7 facts you should know about it

Sleuthing Leads to New Findings About Peculiar Ocean Fish

Opah on animalspot.net

Meet the Comical Opah, the Only Truly Warm-Blooded Fish

10 Cool Facts About Polar Bears

10 facts, Marine Mammals, Polar Bears
Female polar bear with her twin cubs photo by:Photo on <a href="https://visualhunt.com/re/7fdb09">Visual Hunt</a>
Female polar bear with her twin cubs photo by:Photo on Visual Hunt

1. A polar bear’s skin (under its white fur) is actually black to help keep it warm. A polar bear’s white hairs are hollow to help it float while swimming.

2. A polar bear can growl, roar, chuff, hiss, whimper and purr.

3. An adult polar bear’s paw is the size of a dinner plate. Its footpads have small bumps on them, like those on a basketball, so the polar bear has traction on ice.

4. A sense of smell is a polar bear’s strongest sense. A polar bear can smell seals from several miles away.

5. Polar bears mainly eat ringed seals, but also eat bearded, harp and hooded seals as well as carcasses of beluga whales, walruses, narwhal whales, and bowhead whales.

6. Male polar bears are about 9 feet long (2.7 m) and weigh 1000 pounds (453.6 kg). A female polar bear is 8 feet long (2.4 m) and weigh 500 pounds (226.8 kg) (unless pregnant).


7. In the summer, a polar bear may not eat for 3 months. A mother polar bear won’t eat for 5 months while in a birthing lair. Polar bears do not hibernate.

8. Polar bears can hold their breath for 2 minutes. They doggy paddle with their front paws and steer with their rear paws while swimming.

9. A mother polar bear usually has twin cubs. At birth, cubs are the size of guinea pigs. They emerge from their den 3 months after being born so their mother can feed. They leave their mother after 2.5-3 years.

10. Polar bears can run faster than humans, but only for a few seconds.

Facts from children’s book The Polar Bear by Jenni Desmond

10 Tiger Shark Not-So-Scary Facts

10 facts, Elasmobranchs, Sharks, sharks
notice the beautiful tiger-like stripes on the Tiger Shark photo by Edwar Herrano
notice the beautiful tiger-like stripes on the Tiger Shark photo by Edwar Herrano via Undersea Hunter Group

10 Tiger Shark Facts

1. A tiger shark’s stripes fade as he gets older.

2. Tiger sharks are the second most dangerous sharks to humans (after great white sharks)

3. Tiger sharks eat a variety of animals, including sea turtles (their teeth can crack their shells), seabirds, stingrays, sea snakes, fish, mollusks, crustaceans, small sharks and dead whales.

4. Tiger sharks will eat literally anything. They have been found with garbage, plastic bags, license plates and old tires in their stomachs.

5. Tiger sharks on average grow to 10-14 feet long(3-4.3m) (but can grow up to 20-25 feet long [6.1m-7.6m]) and weigh 850-1400 pounds (386-635 kg)(up to 1900 pounds [862kg]).

6. The only sharks larger than the tiger sharks are whale sharks, basking sharks and great white sharks.

7. Tiger sharks generally live alone, but when they do come together in groups they have a social hierarchy based on size. The larger sharks get first dibs on the food source, such as a dead whale.

8. Tiger sharks are killed for their fins, skin and meat. Their liver has high levels of vitamin A and are used in supplements. Their fins are used in the dish, shark fin soup.

9. Tiger sharks are considered “near threatened” (to extinction) on the IUCN Red List. They are just one spot above of “least concern.”

And the final tiger shark fact is:
10. A female tiger shark’s gestation period is 14-16 months, and she can give birth to 10-82 pups.
Also see:
Meet Deep Blue-The Largest Great White Shark Ever Filmed

Great White Shark’s Adventure at the Monterey Bay Aquarium

For more information: National Geographic’s Tiger Sharks
Shark’s World Information on Tiger Sharks
Tiger Shark Facts