mesopelagic
Sea's dim middle
Mesopelagic describes the ocean zone between roughly 200 and 1,000 meters deep, where sunlight fades but doesn't disappear entirely—the twilight zone.
Many creatures migrate vertically through this layer, rising to feed at night.
Mesopelagic fish have adapted to near-darkness with large eyes and bioluminescence.
Light-producing deep-sea fish
- hatchetfishBlade-bodied deep-sea fish
- viperfishBioluminescent deep-sea predator
- dragonfishFanged deep-sea fish
- copepodsMinute aquatic crustaceans
krill · jellyfish · cephalopods · decapods · amphipods
Underwater exploration vehicle
- sonarUnderwater detection by echoes
- oceanographyScientific study of seas
- ROVPiloted-from-above underwater craft
- echosoundersInstruments measuring underwater depth
Organism-generated light emission
- counterilluminationLight-producing stealth adaptation
- twilightLight after sunset
- dimnessInsufficient illumination
- scotopicRelating to dim-light vision
penumbra · gloaming · half-light · luminescence · low-light · dusky · crepuscular
Rapid temperature-change layer
- haloclineSharp saltiness change layer
- pressureForce upon contact
- coldLow temperature state
- nutrient-poorLow in essential compounds
Loose waste from decay
- detritivoresCreatures consuming dead material
- scavengersCreatures consuming dead matter
- predationHunting and consuming prey
- nektonSelf-propelling aquatic organisms
lanternfish
Light-producing deep-sea fish
- hatchetfishBlade-bodied deep-sea fish
- viperfishBioluminescent deep-sea predator
- dragonfishFanged deep-sea fish
copepods · krill · jellyfish · cephalopods · decapods · amphipods
submersible
Underwater exploration vehicle
- sonarUnderwater detection by echoes
- oceanographyScientific study of seas
- ROVPiloted-from-above underwater craft
bioluminescence
Organism-generated light emission
- counterilluminationLight-producing stealth adaptation
- twilightLight after sunset
- dimnessInsufficient illumination
scotopic · penumbra · gloaming · half-light · luminescence · low-light · dusky · crepuscular
thermocline
Rapid temperature-change layer
nutrient-poor · isotherm · salinity · aphotic · hypoxic
midwater
Zone between surface and seabed
- aphoticReceiving no light
detritus
Loose waste from decay
- detritivoresCreatures consuming dead material
- scavengersCreatures consuming dead matter
- predationHunting and consuming prey
migrators
Beings that relocate periodically