Nine Mindless Sea Animals
Jellyfish
Jellyfish don't have brains, but they have neurons that carry messages. Jellyfish are heartless and lungless. Thin skin absorbs oxygen. Jellyfish don't have blood or a heart.
Sea urchins
Brainless sea urchins. Mouth nerve ring. Simple nerves in sea urchins. Without a brain, the lantern's neural centre is a nerve ring.
Sea Cucumber
The sea cucumber's neural tissue-lined oral canal sends impulses to its mouth and tentacles. They scavenge rotting debris and algae on the seafloor.
Starfish
Even without blood or a brain, starfish can digest food outside. Even that doesn't make them intriguing. Starfish can regenerate their arms over time.
Sea sponges
Primitive sea sponges lack a brain and internal organs. These stationary animals subsist by filtering water for organic particles and organisms.
Corals
Corals lack brains but have a nerve net. This system spans the animal's mouth to tentacles. There are 6,000 types of corals that vary in colour, size, and shape.
Clams
Clams don't have brains, but their nervous system nevertheless allows them to feel and react. Clams, a type of bivalve mollusk, inhabit both salty and fresh water.
Oysters
Oysters lack a brain but have a nerve system, organs, and a heart. Oysters are filter feeders and can filter 1.3 gallons per hour.
Sea Anemones
Anemones are connected to corals and jellies. Sea anemones have no brain, only a nerve system. Their nervous system reacts to stimuli.