Epipelagic environment• Upper pelagic

– Surface to 200 m

– Neritic• Over continental shelf

– Oceanic• Beyond the shelf

• Correlates to the photic zone– Most of the primary

production

– Phytoplankton

– Zooplankton

Adaptations• Staying afloat

– Increased drag• Increase surface area

• Higher SA/V ratio with small size

– Increased buoyancy• Lipids

• Gas filled floats / bladders

• Lighter ionic concentrations

Simplified food web– Little loss of

energy… more efficient

– Feeds other ecosystems

…in reality is much more complicated…

…Where does it all go?

Habitats at depth

• Below the Epipelagic– Beyond the high light

penetration

– Depths > 200m

• Pelagic zones

• Benthic zones– Bathyl slopes

• 300-2000m

– Abyssal bottoms• Ave 4000m

– Hadal trenches• 6000-11000m

Mesopelagic

• Mid-water organisms are less abundant vs. EpipelagicExamples: zooplankton (krill & copepods); squid; midwater fishes

• Living within a gradient of decrease: temp., food, & light– Some light, but not enough to

sustain 10 production• Only about 20% of epipelagic food

supply sinks to provide at this level

– Many have adapted to make their own light

• Photophores (light organs)– Bioluminescence

– See, be seen, then hide again

Fig. 16.1

Many midwater critters exhibit gradients of red colors. Why?• How far does light penetrate? Of different wavelengths?• How will red pigment appear in an environment absence of red light wavelengths?

Fig. 16.2

Many midwater predators (fish & inverts) are also prey • E.g. Photophores on squid – why the distinct patterns?

– Interspecific & Intraspecific communication

– Protection & defense – counter shading, disruptive colorations

– Startle / confuse predators

Fig. 16.4

Countershading and counterillumination

Camouflage by light and depth

• Transparency• Reduction of silhouette• More important in

mesopelagic than epipelagic because it is one of their only defense adaptions

• Protection from above and from below– Darker dorsal patterns blend in

with dark below– Lighter ventral blend in with

light above

(a & b) Appearance of prey w/out photophores

- silhouettes on a light background (as seen from a predator below)

(b) blurriness caused by water

(c & d) Appearance of prey with photophores

- silhouettes are broken up against the background

Fig. 16.15

Tubular eyes & “double vision”

Tubular eyes provide greater acuity vision (binocular); but this would limit lateral vision. To compensate, extra lateral retina allows directional and lateral vision.

Fig. 16.12

• General diversity is portraid by relatively small size. Why?

• Midwater fish generally have comparatively large mouths. Why?

• Limited food supply• Hinged jaws, lots of teeth, and

unspecialized diets…can’t afford to be picky or pass-up a potential meal

Fig. 16.6

Viperfish Rattrap fish

Hinged, protrusible jaws to accommodate larger prey

Fig. 16.10

• One of the most numerous in the mesopelagic

– Lanternfishes & Bristlemouths

• Feed at upper depths– feed at night

– Safer from predators

• Non-migrators:– Reduce cost…energy

conservation

Fig. 16.9

Oxygen Minimum Zone

•Another rapid decrease below photic zone because:

•Less mixing with surface

•Less O2 produced

•Only have respiration

•Below the OMZ the amount of food drops greatly, therefore less respiration

Fig. 16.18

Deep Sea• Even less resources

– Light, oxygen, DOM, food• Only about 5% of food

makes its way from photic zone to the deep

• Energy saving adaptations– Less developed muscles,

skeletons, & organ systems

– Most consumption goes into growth first, reproduction later

• Compare the bristlemouths of meso vs. deep sea…

• Smaller eyes, less muscle, fewer light organs, less developed nervous and circulatory systems– …weaker bones, poorly

developed swim bladder

Fig. 16.20

Deep-sea Angler fishes:

large mouth to take advantage of the limited prey, and a specialized “lure”

Fig. 16.19

Fig. 16.21

Fig. 16.27

Page 375

Hydrothermal Vent communities

• Deep-sea vents are rich– Supported by

chemosynthetic microbes

– Seep hydrogen sulfide (H2S) and methane (MH4)

– Up to 120oC

Fig. 16.28

Riftia tubeworm

• Plume (gill) absorbs H2S and CO2, pumped in blood where it is converted to food by symbiotic bacteria & extremophiles via chemosynthesis

Fig. 16.29