When you look at a fish, you can usually see the gill openings – called gill slits. Most fish have five gills on each side of the body, right behind their heads.

And behind them, inside the fish, are “an array of bipartite bars.” Instead of continuous slits supported by a single structure, this fish had pairs of gills supported by pairs of bones.

As the fish closes its mouth, the flap opens. Oxygen is extracted from the water as it passes over the gills. Other fishes have gill slits. Tails: Fish tails also take many shapes.

Feeding Fish Use Crossflow Filtration Date: July 26, 2001 Source: University Of California - Davis Summary: Goldfish might look as if they are just swimming around with their mouths open, but what ...

The gill slits are lined with gill rakers, which look a great deal like baleen that the whales use to strain plankton and krill from the sea water.

These slits evolved into the gill slits of fish and other marine vertebrates, which became specialized to extract oxygen from water and, in the process, lost their ancient filter feeding role.

The fish breathes” oxygen dissolved in water, which it takes in by its mouth and expels through its gill-slits, the gills on its gill-arches being organs of respiration.

Further, the pectoral and pelvic arches originated, each from a group of gill-arches, and hence from groups of appendages of the prot-arthropod. The fish evolved before Cambrian time. But the course ...

ROYER: They were closing their gill slits and preventing that water from flowing across their gills that would cool their body down. BRUMFIEL: They're holding their breath.

As the fish closes its mouth, the flap opens. Oxygen is extracted from the water as it passes over the gills. Other fishes have gill slits. Tails: Fish tails also take many shapes.

Fish don't swallow much water with their food, so somehow food and water are separated. Look in the mouth of one of these fish, and you'll see a series of arches lined with combs called gill rakers.