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explains some scientific terms used in the website.
Adaptation: The features and behaviour of living
things that help them better survive in their environment.
Adductor muscle: In bivalves,
the muscle that keeps their shells shut.
Algae: See seaweeds.
Antennae: A pair of long, jointed, flexible
structures on the head used to sense the surroundings. Compare with
Ambush predator: A predator
that does not actively hunt its prey. Instead, it hides and waits
for prey to come within reach (thus they are sometimes also called
sit-and-wait predators). Some ambush predators rely on camouflage
to avoid being seen by prey. Some may even lure prey closer, e.g.,
While many ambush predators generally don't move about very quickly,
most are able to rapidly snatch prey that comes close enough.
Arthropods: Animals from the Phylum Arthropoda.
Their bodies are supported by a hard outer casing (called the exoskeleton)
instead of a back bone. They have jointed limbs. Arthropods include
insects, spiders, crabs and prawns.
Ascidians: Animals from the Class Ascidiacea.
These animals belong to the same Phylum Chordata as us vertebrates.
Vertebrates belong to the Subphylum Vertebrata while ascidians belong
to Subphylum Urochordata.
Autozooid polyps: In leathery
soft corals, these are polyps with long stalks and tiny branched
tentacles that emerge from the shared tissue.
See also siphonozooid polyps.
Axial corallite: In branching acropora
corals, it is the large corallite at the tip of the branch. See
also radial corallite.
Blade: the leaf-like portion of a seaweed.
Bilateral symmetry: Symmetrical in two halves. Humans are bilaterally
symmetrical. You can draw a line down the centre of our body and the
left and right side should be more or less identical. See also symmetrical
along five axes.
Bivalves: Animals from the Phylum Mollusca,
Class Bivalvia. They usually
have a hinged two-part shell. Examples include mussels,
Bryozoans: Animals from the Phylum Bryozoa.
Byssus threads (sometimes spelt byssal): Tough, adhesive fibres
produced by bivalves to attach
themselves to a firm surface. A gland in the foot produces these fibres.
Examples of animals that produce byssus threads include mussels
and Fan shells.
Calcareous: made of calcium carbonate, thus
usually hard or sharp.
Camouflage: An animal's shape, colour or pattern that allow
it to blend in with its surroundings so it is less likely to be noticed
by predators or prey.
Capsule, egg: see egg capsule
Carnivore: An animal that eats the flesh of other animals.
Case, egg: see egg capsule
Cerata: In some sea slugs
and nudibranchs, these
are the many projections on the body, often finger-like, but sometimes
also leafy such as in the Bushy
Chlorophyll: See photosynthesis.
Cilia: tiny hairs, usually beating hairs that create a current.
Found on various body parts of various animals for various uses. In
some animals, cilia play a part in gathering or moving food.
Cirri: In feather
stars, it is the claw-like appendage on the underside that the
animal uses to grip the surface.
Class: See about scientific
Cnidarians: (Pronounced 'nai-day-rians', the 'c' is silent.)
Animals from the Phylum Cnidaria.
All are aquatic and one of the features unique to them are stinging
cells used for protection and to catch prey. Examples include jellyfish,
sea anemones and corals.
Colonial animals: In cnidarians,
ascidians and bryozoans,
a colonial animal is made up of individual animals, called zooids,
that are structurally joined to one another and share resources. Examples
include hard corals
pens. See also polyp and zooid.
Corallite: The skeleton produced by a single polyp
of a hard coral.
Crustaceans: Animals from the Phylum Arthropoda, Subphylum
Crustacea. Most are marine and most have two pairs of antennae. Examples
include crabs, prawns and barnacles.
Deposit feeder: An animal that collects food
particles which settle on the sea bottom. For more
Detritus: Dung and decaying matter. A detritivore is an animal
that eats detritus. For more details
Dorsal fin: See fins of a fish.
Echinoderms: (Pronounced 'ee-kai-no-derms'.)
Animals from the Phylum Echinodermata.
They are symmetrical along five axes and have tube feet and spines.
Examples include sea stars, brittle stars, sea cucumbers, sand dollars
and sea urchins.
Ecosystem: Here are more
Edible: In this website, it means the plant or animal is eaten
by humans. These, however, must often first be properly processed
and cooked before they can be safely consumed.
Egg capsule: A protective 'container' for one or several eggs.
The case may be leathery and hard, or gelatinous. Animals that lay
egg capsules include snails and squids. Some examples of egg capsules:
melongena. Some animals lay their eggs in a mass or strings, coils
Encrusting animals: Animals that grow as a thin, spreading
crust or layer over hard surfaces such as rocks and shells. Barnacles
are an example.
Endangered: see threatened
Exoskeleton: See arthropods.
Family: See about
Filter feeder: An animal that collects food particles which
are suspended in the water by actively creating a current through
its body or using body parts as a sieve. For more
Fins of a fish: This diagram shows some
of the types of fins on a typical fish.
Food chain: The transfer of energy as one living thing eats
another and is in turn eaten. A food chain typically begins with the
energy first created by a living thing that makes food through photosynthesis.
Free-swimming larvae: See metamorphosis.
Gastropods: Animals from the Phylum Mollusca,
Class Gastropoda. They generally
creep on a muscular foot. Many have a spiralled shell. Some gastropods
such as slugs, however, lack shells.
Gills: the breathing organ of an aquatic animal. Usually a
complex structure that provides a large surface area for exchange
of oxygen and carbon dioxide with the surrounding water.
Genus: See about scientific
Habitat: Here are more
Herbivore: An animal that eats plants.
Hermaphrodite: An animal with both male and female reproductive
systems. In some animals, both systems are present at the same time.
Other animals may change from one gender to another. Many marine animals
are hermaphrodites. These include some fishes.
Holdfast: the part of a seaweed
that anchors it to the ground or a hard surface. Unlike true roots,
this merely grips the surface and does not absorb water or nutrients.
Intertidal zone: A coastal area that is covered
by water at high tide and exposed at low tide. Why
is the intertidal zone special?; More
Invertebrates: Animals that do not have backbones. Instead,
their bodies are supported by an exoskeleton (as in arthropods) or
body fluids (as in sea anemones). Invertebrates include insects, worms,
snails, crabs, sponges and sea stars. More than 90% of all animals
Larva: See metamorphosis.
Lateral line: In many fishes,
this is a series of special sense organs arranged in a line along
the sides of their bodies. Not all fishes have a lateral line.
Mantle: In molluscs,
it is a a thin, specialised tissue of the body that produces the shell.
Mantle skirt: In nudibranchs,
this refers to the thinner edges of the body.
Mass, egg: see egg capsule
Medusa: In cnidarians,
a medusa is an animal with a jellyfish-like shape: an umbrella-shaped
body with the mouth facing downwards and surrounded by tentacles.
Many cnidarians go through this free-swimming stage as medusae in
their life cycle.
Metamorphosis: Animals that undergo
metamorphosis have a life cycle in which they change shape abruptly
and drastically. This shape change usually takes place during the
larval stage of the life cycle, i.e., just after hatching from the
egg. A larva looks very different from the adult and may go through
several different shapes before eventually taking on the adult form.
Many marine creatures have a free-swimming larval stage during which
they disperse to colonise new places. Here is an
example of metamorphosis in shrimps. Here are some examples of
the typical larvae of some common
Animals from the Phylum Mollusca.
They are soft-bodied and many have a radula. Many,
such as snails and clams, produce a protective shell. Others don’t
have a shell, such as slugs, octopuses, squids and cuttlefish.
Moulting: In arthropods, this is the periodic shedding of the
exoskeleton. The shed skin is called a moult. For more detail on how
this happens in a crab.
In gastropods, this is a trapdoor or lid to seal the opening
in the shell to protect their soft bodies from predators and
drying out. The trapdoor is usually attached to the gastropod’s
foot. On the right is a series of diagrams showing how a snail
uses its operculum to seal the shell opening.
Opistobranchia: a subclass of the Class Gastropoda.
Most opistobranchs are slug-like with a reduced shell or no
shell at all. They include sea
slugs and nudibranchs.
Oral disk: In cnidarians
such as sea
anemones, this is the flat circular portion of the animal
with an opening in the centre that functions as a mouth. The
oral disk usually also bears tentacles
around the 'mouth'.
Oral tentacles: In sea
hares and some nudibranchs,
these are the pair of tentacles near
the mouth. See also rhinophores.
Oral veil: In some nudibranchs
such as armina,
this is the shield shaped structure in front of the mouth.
Order: See about scientific
Osphradium: In gastropods,
a sensory patch near the front of the animal that helps it sense
Ossicles: In echinoderms,
these are plates made of calcium carbonate that form the internal
skeleton of the animal.
a snail uses its
operculum to seal
the shell opening
Papulae: in echinoderms,
these are tiny transparent finger-like structures that appear on the
upperside of a sea
Parapodia: In sea
hares and sacoglossans,
this is a pair of 'wings' or flaps that cover the centre part of the
Pectoral fin: See fins of a fish.
Pedal disk: In cnidarians
such as sea anemones,
this is the flat circular portion of the animal at the base of the
body column. This may be used to cling to a hard surface or to anchor
the animal in the sand or a crevice among corals or coral rubble.
Pedicellariae: In some echinoderms
such as sea stars
and sea urchins
dollars, these are tiny pincer-like structures found all over
the body. They are used to keep the body clear of parasites, encrusting
organisms and debris.
Periostracum: fine hairs growing on the shell of bivalves
or marine snails (gastropods).
Petaloid: In some echinoderms
such as sand
urchins and heart
urchins, this is the petal-shaped pattern on the upper side of
the skeleton. The pattern is made up of a series of tiny holes in
the skeleton. Tube feet emerge through these holes.
Pelvic fin: See fins of a fish.
Pharynx: in flatworms,
a part of the gut that can be pushed out of the mouth to engulf prey.
Photosynthesis: A process that uses sunlight
to make food from simple chemicals. Nearly all plants can carry out
Phylum: See about scientific
Phytoplankton: See plankton
Pinnules: In feather
stars, these are tiny finger-like structures that arise in rows
along the arms and which give the animal its feathery look
Plankton: Microscopic plants and animals
that drift in the sea, some examples.
Microscopic plants are called phytoplankton, while microscopic animals
are called zooplankton.
Poisonous: A poisonous living thing can
harm if it is eaten because it produces toxic substances. Not all
poisonous organisms are venomous. For example,
you are unlikely to die if a pufferfish bites you, but you may if
you eat it.
Polyp: In cnidarians,
a polyp is an animal with a cylindrical body which is attached at
one end. The other end has a central mouth surrounded by tentacles.
A sea anemone is a large, solitary polyp. A coral is made up of many
small polyps that are structurally joined to one another as a colonial
A sea anemone is
a solitary polyp
coral is a colony of many
small polyps joined to one another
Predator: A carnivore (flesh-eating
animal) that hunts, kills and eats other animals. Some predators,
however, may not actively hunt their prey and simply hides and waits
for prey to come within reach. These are called ambush
Prehensile: adapted for grasping, especially for wrapping around
an object. The seahorse,
for example, has a prehensile tail to grip surrounding objects.
Prey: An animal that is hunted, killed and eaten by a predator.
Proboscis: A long, retractable tube located on the head. In
gastropods, this is an extendible
tube which contains the radula, mouth and gullet.
Prosobranchia: a subclass of the Class Gastropoda.
Most prosobranchs are snails with well developed shells and breathe
Pseudotentacles: in a flatworm,
a pair of ear-like structures at the front end of the animal made
out of folded edges of its body. Pseudotentacles are not 'proper'
tentacles like those of a snail.
a subclass of the Class Gastropoda.
Pulmonates can breathe atmospheric air. The gills are reduced or lost
and the mantle cavity works like a lung. Few pulmonates, however,
are marine. Most are found in freshwater or on land and include slugs
and land snails.
corals, these are the corallites that emerge around the
sides of a branch. See also axial corallite.
A tongue unique to molluscs.
It is usually a strip or ribbon of flesh covered with tiny,
hard teeth. The radula is often used like a file. The features
of the radula matches the diet of its owner, e.g., to rasp off
algae or drill through a shell. In some, the radula is modified
into a piercing organ to inject venom.
Rhinophores: In sea
hares and nudibranchs,
these are tentacles found on top of
the 'head'. These are believed to 'smell' or detect chemicals
in the search for food and mates. See also oral tentacles.
Red tide: A sudden 'bloom' of toxic micro-organisms that
multiply so quickly that they stain the water red. These micro-organisms
are concentrated in filter-feeding animals such as bivalves.
People that eat such animals may become seriously ill. More
on the bivalve fact sheet.
Scavenger: A carnivore (flesh-eating
animal) that eat animals which are already dead.
Sclerites: tiny, often microscopic, hard pieces that
are found in the tissues of soft corals. Positive identification
to species often requires examination of sclerites. Also sometimes
called spicules, but it's more correct to call them sclerites.
Septa: In hard corals, the skeleton walls within a corallite,
the skeleton formed by one polyp.
a grazing snail uses its radula
like a file to scrape off food
radula is retracted
when the snail is not eating.
eat, the radula is extended and
used to scrape food into little bits
that are then swallowed.
Siphon: A tube to suck in or eject water. A siphon may
be used to suck in water to get oxygen and food. This is particularly
useful for burrowing animals. Or to analyse the chemicals in the water
in order to find food or mates. Water may be flushed out through a
siphon to get rid of wastes. Animals with a siphon include gastropods.
A siphon is used for jet-propulsion in octopuses, squids and cuttlefish.
Siphonal canal: the edge of a snail's shell that forms a notch
through which the siphon emerges.
Siphonozooid polyps: In leathery
soft corals, these are polyps that don't emerge from the shared
tissue and function as water pumps for the colony. See also autozooid
Slugs: See slugs.
Species: See about scientific
Spicules: see sclerites
Sponges: Animals from the Phylum Porifera.
Stinging cells: In cnidarians, these are special cells used
to gather food or for protection. See cnidarians
for more about them and diagrams of how the stinging cells work.
Stipe: the stem-like portion of a seaweed.
Subphylum: A sub-category of a Phylum. See about
Suspension feeder: An animal that collects food particles which
are suspended in the water. For more
Symbiosis: A relationship where two different species interact
closely with one another. For more
Symmetrical along five axes: An animal that has this feature,
such as a sea star, has a body made up of five equal parts. All echinoderms
have this feature. Here are some diagrams
of symmetry along five axes in echinoderms. See also bilateral
Tentacles: Long, slender,
flexible structures used to sense the surroundings or to gather food.
Compare with antennae and pseudotentacles
Test: In some echinoderms
such as sand
urchins and heart
urchins, this is their internal skeleton. The test is made of
ossicles (pieces of calcium carbonate) fused together into plates
usually in multiples of five. The test is spherical in sea urchins,
sometimes oval in heart urchins and flat like a coin in sand dollars.
Spines are usually attached to the test, and this entire assembly
covered in skin. When the animal dies, the skin decays and the spines
fall off, leaving behind the test without spines.
Thallus: the whole seaweed is called the thallus.
Threatened plants or animals: They are endangered (in immediate
danger of extinction) or vulnerable (may become endangered in the
near future). A list of threatened plants and animals of Singapore
can be found in The Singapore Red Data Book. ( Ng, P. K. L.
& Y. C. Wee, 1994. The Singapore Red Data Book: Threatened
Plants and Animals of Singapore. The Nature Society (Singapore),
Singapore. 343 pp.)
Tides: more in about tides
Tide, Red: see Red Tide
Torsion: A developmental stage in gastropods.
Toxin: A substance produced by a living thing that can harm
or kill other living things. See also poisonous
Tube feet: In echinoderms,
these are tiny hollow tubes. An echinoderm changes the shape of its
tube feet by adjusting the water pressure in the tube feet. Tube feet
often end in suckers. Tube feet may be used to cling to things, gather
food, excrete wastes, breathe and sense chemicals.
Tunic: In ascidians,
the sturdy outer coating of the animal.
Venomous: A venomous animal
can harm by injecting a toxin. The toxin may be introduced by biting
or stinging. Not all venomous animals are poisonous.
For example, you may safely eat a venomous animal like a stingray.
Verrucae: Small spots or bumps on a sea
anemone's body column and underside of the oral disk. Some may
be adhesive (sticky) and used to grip the ground or to help keep the
oral disk flat against a hard surface. In others, they are not sticky.
Warning colours: Bright colours or patterns
that make an animal stand out from its surroundings in order to advertise
its venomous, poisonous or otherwise unpleasant nature, thus deterring
Water vascular system: In echinoderms,
this is a network of internal canals supported and pumped mainly with
seawater. By expanding or contracting chambers in the system, the
water pressure in the canals can be directed and changed. The system
allows the echinoderm to move and perform many life functions.
Zooxanthellae: (Pronounced ‘zoo-zen-the-lay’.)
Microscopic, single-celled symbiotic algae that may live in symbiosis
with animals such as corals and sea anemones. The
algae undergo photosynthesis to produce food from sunlight. The food
produced is shared with the host, which in return provides the algae
with shelter and minerals. For more
Zooid: A colonial ascidian
or bryozoan is made up of tiny
individual animals called zooids that are structurally joined to one
another and share resources. See also colonial animals.
Zooplankton: see plankton.