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Marine Biology B—Marine Invertebrates: Body Plans, Movement & Minds Without Brains
by MonaA tour of the ocean's spineless majority — from sponges to octopuses. Learners discover how evolution built radically different body plans, then explore how animals without backbones (and often without brains) move, sense, and solve problems.
Library
Invertebrate Diversity: Blueprints of the Animal Kingdom
Lesson 1
The Animal That Failed the Animal Test
There's a creature on the reef with no mouth, no muscles, no nerves, and no brain — it hasn't moved in decades — yet biologists insist it's just as much an animal as you are. What do they know that your definition misses?
StartLesson 2
How Does Something So Soft Hunt?
Jellyfish and anemones have no teeth, claws, or speed — yet they catch fast-moving prey. What's their secret?
Locked till you take the prior lessonLesson 3
Why Do Animals Have Heads?
Plenty of animals get by without one. So what pushed some ancient creatures to evolve a front end at all?
Locked till you take the prior lessonLesson 4
One Body Plan, a Thousand Lives
A garden snail, a clam, and a giant squid are close relatives. What could such different animals possibly share?
Locked till you take the prior lessonLesson 5
The Price of Wearing Armor
A crab's shell protects it from almost everything. So why is it also the most dangerous thing about being a crab?
Locked till you take the prior lessonLesson 6
The Animal That Broke the Rules
Every complex animal has a head and two matching sides — except one strange group. What happened to sea stars?
Locked till you take the prior lessonLesson 7
Why Don't Baby Sea Animals Look Like Their Parents?
A baby crab looks nothing like a crab. A baby sea star could pass for a different species. Why live a double life?
Locked till you take the prior lessonLocomotion & Behavior: Minds Without Brains
Lesson 8
Moving Without Bones
No skeleton, no fins, barely any muscle — yet jellyfish and squid travel the open ocean. How do you swim with a body like that?
Locked till you take the prior lessonLesson 9
How Can a Worm Dig Through Solid Sand?
You can't push a rope, and a worm is basically a soft tube. So how does it force its way through packed seafloor?
Locked till you take the prior lessonLesson 10
The Sea Star's Impossible Grip
A sea star can slowly overpower a clamped-shut clam — with no muscles strong enough for the job. What's really pulling?
Locked till you take the prior lessonLesson 11
Who's in Charge When There's No Brain?
A jellyfish hunts, swims, and reacts to danger without a brain. So what, exactly, is making its decisions?
Locked till you take the prior lessonLesson 12
Sensing a World We Can't Imagine
Some invertebrates detect things no human ever could. What is the ocean like when you sense it with a completely different toolkit?
Locked till you take the prior lessonLesson 13
Evolution's Other Experiment with Intelligence
One invertebrate solves puzzles and seems to plan ahead — yet its mind is built nothing like ours. What is it like to be one?
Locked till you take the prior lesson