“Tentacles” Basic Facts
What exactly is a cephalopod?
- A mollusk, related to snails, clams, mussels and sea slugs. Common body structure including: bilaterally symmetrical body, a mantle which acts as a skin-like covering, three hearts, blue blood (when exposed to air), file-like tongue called a radula, a head surrounded by a ‘foot’ which has evolved into arms and/or tentacles.
- More than 800 species of cephalopods have been identified so far; scientists suspect there may be as many as 1,000.
- Difference between octopuses, squid, nautiluses and cuttlefishes
- All species except the nautiluses have suckers on their tentacles and arms
- Octopus don’t have tentacles, they only have arms
- Squid and cuttlefishes have eight arms and two retractable tentacles
- Nautiluses are one of only a few cephalopod without an ink sac
- All cephalopods, except nautiluses, have acute vision that they rely on to avoid predators and detect prey.
- All octopuses and most other cephalopods are color blind – surprising considering they are adept at changing colors.
A Closer Look
- Have head and eyes, mantle and siphon, beak and radula, no ink sac and up to 100 tentacles without suckers.
- Have head and eyes, mantle and siphon, beak and radula, an ink sac and eight arms with two tentacles with suckers; some squid species have hooks on their arms and serrated “teeth” in their suction cups.
- Have head and eyes, mantle and siphon, beak and radula, an ink sac and eight arms with one or two rows of suckers but no hooks or sucker rings.
- Have head and eyes, mantle and siphon, beak and radula, an ink sac and eight arms with two tentacles with suckers.