Mouth
Spine
Feet
Nose
Strongylocentrotus
Animalia
Purpuratus
Echinoderms
Small fish
Algae
Sea cucumbers
Other sea urchins
Both intertidal area and subtidal areas
On the beach
Intertidal area only
Subtidal area only
Because sea urchins have large numbers of eggs
Because sea urchins have large numbers of relatively big eggs
Because a sea urchin's egg is relatively big
Because the eggs make great omlettes
Porcupine
Dome
Pentamerous
Toothpick