The Magical Mollusc Adventures

Of Tony and Yasen

10/5

Molluscus: The Name• Molluscus – “thin shelled”;• τᾲ μαλάκια – “the soft things”[1];

Major Mollusca classes• Gastropoda - snails, slugs, etc.• Bivalvia – clams, mussels, etc.• Cephalopoda – squids, octopi, etc.

Evolution and Symmetry

• Symmetry – bilateral[2];• Humans – mollusca – 550 mil;• Mollusca – arthropoda – 50 mil;

Derived Characteristics• Mollusca diversity – “generalized

mollusc”;• Shell (1), mantle (2), foot (3) [3];

Nervous System• 2 pairs of nerve cords;• Visceral – internal organs;• Pedal – movement;• 2 nerve masses – ganglia –

coordinating signals[3];

Locomotion• Variable across species;• Herbivorous (snails e.g.) – gliding –

wave contraction;• Carnivorous (octopus e.g.) –

lifestyle - jet propulsion;• Others – maneuverability –

burrowing e.g.;

Eek!

Gas exchange, food intake, waste disposal• Aquatic molluscs have gills.• Land molluscs have lungs (gasp)• Most molluscs have a toothy tongue,

named radulae[1]

– For scraping bacteria off rocks

• Waste is eliminated via the anus at the back of the body. :>

Mollusc Hall of Fame(and importance)

SSS kingdom. Snail, slug, and squid. Slime may vary.

• The Awe-Inspiring Giant Tiger Snail (Achatina achatina)

• Elysia chlorotica, that kleptomaniac sea slug! (Rudman)• Pickfordiateuthis pulchella, the liliputian squid!

HR: Human Relationships

• Most snails are considered pests :<– Often poisoned in order to keep the

garden safe• Sea slugs often used for filtering

aquarium water (from bad organisms) [4]

• The hunt for the biggest squid is ongoing. Woe the squids.

Trivia Answer of the Day

• Mollusca is the largest marine phylum – 23% of all marine species!

• The Gastropoda mollusc class is second in numbers only that of the insects![1]

The End

And that’s a squid.

You just can’t see the tentacles…