Bryozoans

Bryozoans

Bryozoans are colonial animals of uncertain evolutionary descent. They may be related to freshwater rotifers. Bryozoans are found in the lower intertidal to subtidal zones, attached to a firm substrate, and also in brackish water. Individual animals are too small to see with the naked eye.

Bryozoan growth forms range from encrusting, forming coatings on hard surfaces, to bushy. An entire colony may bear a superficial resemblance to a hydroid colony, although bryozoans are internally more advanced than cnidarians. Bryozoan colonies grow to 3", and are occasionally larger.

Bryozoan anatomy
Note separate mouth and anus, unlike hydroid
Spiral Tufted Byozoans
Spiral Tufted Byozoans Amanthia spp

From way back when in 1996 ...

NJ Scuba
Diving Myths
by Dr. Jolie Bookspan, author of Diving Physiology in Plain English

Myth 1 - The Dive Reflex Protects You

diving myths

In the dive reflex, heart rate and limb blood flow decrease. Careful science ( that means we didn't accidentally step on the thermisters ) shows time and again that the dive reflex does not reduce the need for oxygen underwater as it does in marine mammals. Field studies ( where you're allowed to step on the thermisters ) indicate that the dive reflex does not extend breath-holding time. Occasional cases of human survival after very cold water near-drowning are not due to the dive reflex. Cold is the likely mechanism behind the reduced metabolism that permits survival.