Oceans 11 – Notes (Cont.)
The Mesopelagic Zone
-This zone extends from the bottom of the epipelagic zone (200 m deep) down
to the edge of the bathypelagic zone (1000 m deep).

Although the top 100 m of the mesopelagic is in the photic area, the rest of it is
in the aphotic area.

Because of this, the mesopelagic has been called the twilight zone.
-Since photosynthesis is impossible here, marine snow is an important source of
food in the mesopelagic.

Only about 20% of the food created in the epipelagic zone makes it down this
far, so many creatures have to spend some of their time in the epipelagic zone
to feed.

Most mesopelagic creatures who rise into the epipelagic for food do so at night,
to avoid predators.
-Organisms living in this zone have to deal with increasing water pressures and
much cooler water temperatures.
-Most species also have adaptations to deal with the lack of light, such as very
large eyes.

Many mesopelagic animals possess bioluminescence. This means they can
produce their own light.

Bioluminescent cells inside theses organisms are called photophores.

Some fish, shrimp and squid have photophores on their undersides that match
the surface brightness. They can reduce the light during cloudy days, and boost
it when it is sunny. The photophores may be turned off at night to make the
animal almost invisible.

Bioluminescence can also be used to attract a mate or to stun a predator while
the light-producing animal makes a getaway.
-Fish who call the mesopelagic zone home include hatchetfish, lanternfish,
bristlemouths, coelacanth, and anglerfish.

They are joined by species of krill, jellyfish, octopus, squid, worms, and shrimp.
-In general, the mesopelagic zone has much less life than the epipelagic and is
very empty by comparison.