Dissecting a Squid

SCIENCE CONCEPT:

Jet propulsion is a very different form of locomotion in the water. The simplest example of this can be seen in jellyfish. The more complex animal using jet propulsion is the squid.

STUDENT OBJECTIVE:

OVERVIEW:

The student will use a penny, a drinking glass, and a card to discover that an object at rest remains at rest unless acted upon by an outside force.

PREPARATION TIME:

20 minutes.

LESSON TIME:

45-60 minutes.

TEACHER PREP:

Locate enough squid for every two students in the classroom. They will dissect the squid in pairs.

WORDS TO KNOW:

propulsion

expulsion

muscular

mantle

siphon

ink sac

sucker

tentacle

funnel

gills

pen

TEACHER TEXT:

Another very different form of locomotion in the water is jet propulsion. The simplest example of this can be seen in jellyfish. These animals fill their umbrella section with water and then push the water out, sending the jellyfish in the opposite direction. Salps are another simple animal that uses jet propulsion to move. These animals are related to sea squirts and live in large chains, some as long as 100 feet.

A more complex animal using jet propulsion is the squid. Some squid are able to reach speeds high enough to shoot them out of the water and onto the decks of passing ships! The squid has a muscular mantle which, when expanded, fills with water. When these muscles contract, water is expelled through a single siphon and the squid is propelled the opposite direction. Unlike jellyfish, the squid can control its direction by rotating the siphon. Often the expulsion of water is accompanied by a puff of dark ink from the squid's ink sac in order to deter predators from following.

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Last modified: Sat Aug 23 14:04:12 PDT 1997