Hadal: The deep sea region below 20,000
feet (6,100 meters); the deep trenches.
Hake: A fish, related
to cod, that gathers in large schools. Hake live from the surface down
to depths of 3,000 feet (914 meters).
Halibut: A large fish
with a flattened body adapted for life on the seafloor.
Haptera: Rootlike structures growing from
the base of a kelp plant. Haptera form the holdfast that anchors the
kelp to the seafloor.
Harems: Large numbers of females that mate
with one male.
Harlequin shrimp: A colorful shrimp from
the coral reefs of the central Pacific.
where eggs and sperm are fertilised and immature stages are matured.
Used in aquaculture.
Haul out: To climb up out of the water.
Seals often haul out onto rocks.
Head of the canyon:
The shallow part at the beginning of an underwater canyon.
Hectopascals: Unit of measure for high or
low pressure systems.
Herbivore: A plant eater.
Hermaphrodite: An animal that has both male
and female reproductive organs.
Hermit crab: A crab
that protects itself by living inside an empty snail shell. There are
many species of hermit crabs, some on land, some in the
Herring: A small, silvery fish that swims
in large schools.
Holdfast: The root-like base of marine
algae that anchors or attaches the plant to the substrate. The
root-like part of the thallus.
Holding pens: Large
tough plastic holding tanks for fish grown in aquaculture.
Hookah: Air pumps in a boat pumping air to
divers below through a tube. Used by abalone divers.
line: Any fishing method which uses a sharp hook (baited or
not) attached to a nearly-invisible fishing line. Different
hook-and-line methods include longline, troll and
Horizontal: Side-to-side, or stretched out
flat like the horizon (opposite of vertical).
Hull: Frame or
body of a ship.
Humus: Nutrient-rich earth formed when
plant material decays.
Hydrological cycle: See water
Hydrodynamics: The study of fluids in
motion and the movement of objects through fluid.
calibrated instrument for measuring the specific gravity of a
Hydroid: A body shape often taken on by
animals related to sea anemones. A hydroid has a fleshy central stalk
topped by a ring of tentacles used for catching food. Anemones are one
kind of hydroid; many jellies are hydroids for part of their
Hydrothermal vents: Beaks in rocks where
warm or hot fluids seep out.
dangerous loss of body warmth, which can cause death.