GD Second Timers: Bones 2 (E-H)

Fish gill lamellae (secondary) stand up straight. The blood flow in them runs the opposite direction to the water flow coming in through the gills.

A tuna fish can weigh up to 1500 pounds!

What covers the gills to protect them is the skin layer called the popacitum.

A nudibranch sea slug has very unusual gills. They are located in the slime-secreting “foot” that it slides on.

Between the osteon rings there are living osteocytes which are imprisoned in bone.

There is a pipe—a cave—in the center of each osteon called the Haversian Canal. In this hollow tube there are blood vessels, lymph “pipes” and nerves.

The trabeculae bone in this picture are also called:

The pinpoint openings in the trabeculae spongy bone above lead to “caves” called canaliculi.