Squid

by Mr. Driedger

Description

• Squids are mollusks, similar to octopuses, but with a few major differences.
• They have eight arms and two long tentacles with suckers.
• They usually only live for one year, and they die after they spawn (reproduce).
• Most species of squids are no more than 60 centimeters long, but they range from tiny carribean reef squids (20 centimeters) to giant squids and colossal squids which can be up to 13 or 14 meters long!

Habitat

• They live in oceans all over the world, especially around coral reefs.
• The Great Barrier reef is home to about 4000 different types of mollusks, about 300 of which are squids.

Predator Adaptations & Feeding Habits

• Squids are carnivores that eat smaller fish, such as the Clownfish and the Parrot Fish.
• They use their long tentacles for catching and pulling in prey.
• They are fast-moving and fast-growing.
• Squids have a sharp beak made out a hard material called chitin that they use to kill and tear apart fish.

Prey Adaptations

• Squids often camouflage with their surroundings so they can hide form predators, such as the Moray Eel and the Reef Shark.
• Although they don’t have vertebrae (backbones), they do have one big flat bone inside for defense, like an internal shell.
• Squids can expel ink to blind predators while making an escape.

Symbiotic Interactions with Other Species

• There is a mutualism symbiosis relationship between some squid and the bacteria “vibrio fischeri”. These light-producing bacteria are drawn into an organ on the bottom of the squid.
• The bacteria benefit by having a place to live, and source of food.
• The squid benefit because the bacteria help them avoid predators. When predators look up from the deep ocean, the surface looks bright. Without these bacteria, squids would appear as dark blobs against the bright ocean surface, and they would be easy for predators to notice. But with these glowing bacteria, they blend in with the bright ocean surface, being better able to hide from predators.

Species Comparison: Blue-ringed Octopus

Similarities:

• Both squid and octopi live in warm, tropical salt-water.
• They both have life expectancies ranging from half a year to five years.
• They are both members of a class of mulluscs called cephalopods, as are the cuttlefish and the nautilus.

Differences:

• Many people make the mistake of confusing squid and octopi, but they are very different species.
• Whereas squid have 8 arms and 2 tentacles, all octopi only have 8 arms
• Some species of squid can grow up to 20m long, whereas octopi can only grow up to 5m long, and the blue-ringed octopus can only grow to 20cm long.
• Octopi have no type of skeleton, but squid have a hard internal shell.
• Octopi live ont he bottom of the ocean and eat crustaceans. Squid live out in the open water, and eat both crustaceans & fish.

Resources

1. Life Magazine, 2003. The Seven Wonders of the World. p 60-63.
2. Tracy Staedter, Sep 25, 2005. Scientific American. Live Giant Squid Photographed for First Time http://www.sciam.com/article.cfm?chanID=sa003&articleID=00030326-0783-133B-878383414B7F0000
3. Encarta Academic Online: Squid. http://encarta.msn.com/encyclopedia_761552165/Squid.html
4. University of Hawaii News. New study reveals secret of squid-bacterial symbiosis. http://www.hawaii.edu/ur/News_Releases/NR_Sept00/squid.html
5. Wikipedia. Squid. http://en.wikipedia.org/wiki/Squid
6. Wikipedia. Carribean Reef Squid. http://en.wikipedia.org/wiki/Caribbean_Reef_Squid
7. Wikipedia. Giant Squid. http://en.wikipedia.org/wiki/Giant_squid