– Chapter 16 (Ocean Depths)
• Know the order of pelagic zones from the surface to the ocean floor: epipelagic, mesopelagic,
bathypelagic, abyssopelagic
• Know that the epipelagic zone is photic and photosynthesis occurs throughout this zone
• Know that the mesopelagic zone is the ‘middle zone’ (where we find “midwater fish”) and that
some light penetrates here, but that it is insufficient for photosynthesis
• Know that the bathypelagic and the abyssopelagic zones are perpetually dark and cold
• Understand that animals in the mesopelagic zone are relatively small (less than 10 inches)
• Understand that most midwater (or mesopelagic) fish have huge, extendable jaws equipped
with fearsome teeth
• Understand that to conserve energy, most midwater animals are ‘sit and wait’ predators, have a
slow metabolism, and have flabby, watery bodies
• Understand that many midwater fish have upward-looking eyes to detect silhouettes of fish
moving above them
• Know that most midwater fish possess photophores which produce a light that matches the
natural light above them, breaking up their silhouette; understand that most photophores are
found on their ventral surface for this reason
• Understand that lanternfish (Myctophiids) are believed to be the most abundant of all
mesopelagic (midwater) fish and feed on the vertically migrating zooplankton
• Understand that deepwater (bathypelagic and abyssopelagic) fish employ bioluminescence, but
not for counter-illumination (no light, even looking up)
• Understand that because no natural light penetrates to these depths, the eyes of deepwater fish
are small (needed only to detect bioluminescence)
• Understand that because mates here are sparse, most deep water fish are hermaphroditic
• Understand that the male anglerfish attaches (and parasitizes) the female anglerfish as a
strategy to ensure reproduction (female feeds and gains energy to produce eggs, male
constantly supplies sperm)
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