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