Bladderfish

This unusual herbivore appears to be mostly defenseless, and bears little resemblance to the other lifeforms around it.

1 Semi-permeable Bladder

The bladderfish is able to filter air and seawater into its body cavity through a unique membrane which surrounds its spine like a bladder. This allows it to remove and consume organic particulate caught on the way, and adjust its buoyancy.

2 Open-ended Vascular Tubing

Can be angled and contracted to pump out water and achieve low-velocity, guided propulsion.

Largely oblivious to threats, and practically immobile at night, its only identified defense mechanism is that it's composed almost entirely of water, air and cartilage.

Assessment Edible (oxygen may be retrieved from the bladder and added to tanks on consumption); membrane has applications as a natural water filter