A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.

- A -

aeolid nudibranchs

Both dorid and
aeolid nudibranchs are suborder members of the order Nudibranchia, with aeolids (a.k.a. eolids) being a type of nudibranch possessing cerata rather than a feather-like external gill on the back and no rhinophoral sheath. Most of the photos shown on my page are dorid nudibranchs, as are most of the species I have encountered. Generally, aeolids are longer and thinner, and dorids are shorter and fatter. Dorid nudibranchs are named for the sea goddess, Doris, daughter of Oceanus and mother of the Nereides. Aeolids are named after the Greek god, Aeolis, god of the wind.

toward the head or front
ahermatypic coral

the opposite of hermatypic; corals that do not possess zooanthellae (see hermatypic)
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- B -


An outrigger-equipped, manually constructed, canoe-shaped wooden boat commonly used in the Philippines. Often brightly colored, these ubiquitous boats far outnumber other means of sea transport. The smaller bancas typically use small lawnmower-type engines, and large bancas often use second-hand car engines imported from Japan. Normally the motor is directly coupled to the drive shaft and propeller, with no reduction transmission in between.

Banca driver (banca means boat in the Philippine language Tagalog)

city on the southern coast of the main island of Luzon in the Philippines about an hour and a half drive from Manila; well known for its dive resorts and diversity of sea life.

bottom-dwelling; living on the substrate or sea bed

bilaterally symmetrical

descriptive term applied to animals that can be divided into two equal halves by a line drawn down the center.
branchial plume

respiratory structure or external gills, usually located on the dorsal side toward the posterior


small, aquatic, colonial animals; also known as "moss animals"
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- C -

Capone Islands

Two small islands about 1/3 mile off the west coast of Luzon, the main Philippine island where the capital city of Manila is located. Divers commonly refer to "Big Capone" and "Small Capone". Big Capone is about 1/4 mile long, and Small Capone is about 1/10 mile long. Both have excellent beaches with sand and shells. Unfortunately the reefs near the islands have fallen prey to the destruction caused by local dynamite fishing.

A large, hard shell covering an animal's back; part of its shield-like exoskeleton.. Animals with a carapace include turtles, most crabs, horseshoe crabs, and sea spiders.

meat-eating; describes an animal that feeds on other animals
ceras (plural cerata)

long respiratory structure containing parts of the nudibranch digestive system and occurring in parallel groupings along the dorsum

specialized front leg with a large pincer claw known as the chela, seen on arthropods such as crabs or lobsters

in a symbiotic relationship, an association that is clearly to the advantage of one species while not harming the other
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- D -


outer layer or skin

organic fragments of plant or animal matter

occurring in two distinct forms, as in sexual dimorphism, describing  physical differences in the sexual forms of an organism.

describes animals that are active during the day and hide during the night.


referring to the back or upper surface.
dorid nudibranchs

Both dorid and
aeolid nudibranchs are suborder members of the order Nudibranchia, with aeolids (a.k.a. eolids) being a type of nudibranch possessing cerata rather than a feather-like external gill on the back and no rhinophoral sheath. Most of the photos shown on my page are dorid nudibranchs, as are most of the species I have encountered. Generally, aeolids are longer and thinner, and dorids are shorter and fatter. Dorid nudibranchs are named for the sea goddess, Doris, daughter of Oceanus and mother of the Nereides. Aeolids are named after the Greek god, Aeolis, god of the wind.

top surface or back
dynamite fishing

An extremely harmful method of fishing responsible for widespread destruction of reefs throughout the world, especially in the Philippines. During my five-year stay I witnessed a pronounced decline in the reefs near the Capone Islands -- when I left virtually all of the reef above about 30 feet in depth had been noticeably damaged by dynamite fishing. A tactic typically employed by local subsistence fishermen, soda bottles are filled with an explosive substance and a fuse. The fuse is lit and the bottle dropped into the water from a boat, where it sinks a few feet and explodes. The resulting blast can be heard for a mile away on the surface, and many miles underwater -- if you are within a mile underwater you think your dive buddy's scuba tank exploded, and if you are very close your eardrums may be ruptured (as once happened to two members of our dive club). After the explosion, the fish near the blast (the ones that don't sink) float to the surface, where they are scooped up by the fishermen. The reef within a radius of fifty feet or so of the blast is destroyed, which eliminates the habitat for the fish, making them scarcer and less likely to be caught using normal fishing methods. The subsistence fishermen are the ultimate losers, since they depend on the reef for fish to eat, and the fish all seem to disappear due to destruction of their habitat. Dynamite fishing is illegal in the Philippines, but despite widespread government efforts to educate rural fishermen it is very common. Click here to see a photo of an unexploded dynamite charge.
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- F -

facultative symbiosis
a relationship in which one partner may, but does not have to, live with another in order to survive (i.e., the relationship of most host sea anemones to anemonefishes)

a group of related genera (plural of genus)
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- G -


a group of related species

respiratory structure

gorgonian coral 

a group of corals also known as "horny corals", this group of multi-colored animals includes sea fans, sea whips, and sea feathers. They are related to the "soft corals", and both belong to the subclass Octocorallia, with eight-part symmetry. Also see "soft coral" and "stony coral".
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- H -

hard coral
see "stony coral"

plant-eating; describes animals that feed only on plants
hermatypic coral
A reef-building coral with symbiotic zooanthellae in the tissues. The zooanthellae utilize carbon dioxide and sunlight to produce organic compounds that are absorbed by the coral as food, providing the overwhelming majority of nutrition needed by the coral colony. Corals that do not have zooanthellae are called ahermatypic corals, and must rely on capturing prey with the stinging cells in their tentacles.

possessing functional male and female sex organs in the same individual
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- L -

larva (plural larvae)

a developmental stage in an animal: the larva hatches from an egg, looks very small and different from the adult form, eats different food, and usually lives in a different environment from the adult. The veliger is the typical larval stage of molluscs.
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- M -

macro photography

Type of photography employing use of special lenses or attachments allowing close-range photos of a given subject - macro 1:2 means the subject is projected on the negative at half life size, macro 1:1 is life size image on the negative (in this case the dimensions of a 35mm negative) - 2:1 is twice life size projected on the film (about postage-stamp size image, projected on to a larger 35mm negative).

the study of molluscs; specifically, members of the phylum Mollusca ,which contains approximately 100,000 living species and 60,000 described fossil species.

a type of tissue on the body surface occurring only in molluscs.

the change from larva to adult


the form and structure of an organism or one of its parts

form of symbiosis in which two species associate together for their mutual benefit
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- N -


Microscopic harpoon-like stinging organ produced by cnidarians (jellyfish and corals) and contained within a special cell, called the cnidoblast.
Nikonos V camera

Amphibious camera designed by Nikon - very well-suited for macro photography owing to its small size and simple design, though not very durable under heavy use (unfortunately I have owned four). One unique feature of the Nikonos V compared to earlier versions of the Nikon amphibious cameras is its Through-The-Lens (TTL) light metering capability, enabling the camera to regulate the degree of strobe illumination automatically based on the internal spot-meter reading.
Nikonos RS camera

Amphibious camera designed by Nikon to supersede the Nikonos V. Designed as a single-lens-reflex (SLR) camera, it is much more expensive, selling for well over 2000 US dollars (camera body only). It has been discontinued due, presumably, to reliability problems. Earlier generations of Nikonos cameras had rubber o-rings for water seals; the RS has silicon seals, complicating routine maintenance.

describes animals that hide during the day and come out at night.

the top surface or dorsum
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- O -

obligate symbiosis
a relationship in which one partner is obligated (must) live with another for survival (i.e., anemonefishes cannot survive without anemones and are therefore obligate symbionts of sea anemones)


producing eggs that develop within the maternal body (as of various fishes or reptiles) and hatch within or immediately after extrusion from the parent


producing eggs that hatch outside the body; most fish, amphibians, birds, insects and reptiles are oviparous
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- P -


small bulge on the body surface

a symbiosis in which one partner benefits, but the other partner is harmed

living, floating, or swimming in the water column above the bottom; a whale is said to be pelagic, meaning it lives in the open water of the ocean

the manufacture of carbohydrate food from carbon dioxide and water in the presence of chlorophyll, by utilizing light energy and releasing oxygen

marine plants and animals that drift with the ocean's current; they are usually very small but some are large-- including jellyfish

egg-shaped body in plant tissues that contains chlorophyll and is able to photosynthesize

tail end


adapted for seizing or grasping especially by wrapping around, such as a prehensile tail

preopercle, preoperculum

bone between the cheek and the gill cover

feeding structure on an invertebrate, sometimes extendable and equipped with jaw-like structures for holding prey
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- R -


a ribbon of chitinous teeth, found only in molluscs

paired, tentacle-like sensory apparatus found on the head

rose-shaped in appearance; arranged in a fashion resembling a rose flower
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- S -


Self Contained Underwater Breathing Apparatus
sea anemone

Primitive invertebrate animals belonging to the phylum known as either Cnidaria (pronounced with silent "C") or Coelenterata ("se-len-ter-a'-ta). They have a single body cavity that serves as stomach, intestine, circulatory system, etc., and one body opening (the mouth) through which everything passes, in or out. The mouth is surrounded by finger-like tentacles, typically containing stinging cells called nematocysts. The tentacles are used for catching food and transporting it to the mouth or for defense.

descriptive of a family of polychaete worms, Serpulidae, that live in a rigid calcarious tube secreted by the worm. Differ from the sabellids, of family Sabellidae,  that live in flexible tubes constructed of sand grains embedded in mucus. Terms such as tube worm, fanworm, feather-duster worm, Christmas-tree worm, peacock worm, and other common names may be applied to serpulid or sabellid worms, or sometimes both, depending on the reference source.
soft coral
corals that do not surround themselves with a hard, calcified skeleton, and that are members of subclass Octocorallia of class Anthozoa (compared with the hard corals that are members of subclass Hexacorallia). The names indicate the number of arms about the mouth of the coral and the number of symmetric segments of the body ("hex" means six and "octo" means eight). Soft corals come in a wide variety of pastel-like colors and are closely related to gorgonians (also of subclass Octocorallia). Also see "stony coral" and "gorgonian coral".
stony coral
also known as hard or true corals, marine invertebrates of subclass Hexacorallia, class anthozoa, phylum Cnidaria. The most familiar class of corals, with a hard calcareous skeleton, with a color that depends on the algae living symbiotically within the white skeleton. Types of stony corals include mushroom, star, staghorn and brain coral. Also see "soft coral" and "gorgonian coral".

For purposes of underwater photography, artificial light device or flash device used to restore wavelengths of light filtered out by water - the deeper the depth, the less the presence of natural light. With depth, natural light disappears in order according to wavelength - reds disappearing first, violets last. The photos shown here were exposed utilizing either a Nikonos SB-102 or SB-103 strobe positioned a few inches from the subject.

shallow, narrow grooves or indented lines

possessing striae as a characteristic

A close association between two species generally (with the exception of parasitism) seeming to be unharmful to either member, or, more likely, beneficial to one or both. Parasitism, commensalism, and mutualism are the three types of symbiotic relationships.
(see facultative symbiosis and obligate symbiosis)
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- T -


Classification of plants and animals into established groups or categories on the basis of their natural relationships.

Visible but not opaque, able to see through but not transparent.

member of a family of nudibranchs (family name: tritonniidae, suborder Dendronotoida) that feed exclusively on soft corals.
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- U -

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- V -


free-swimming larval stage found only in molluscs, in which the larva has a small shell.

underside; lower part of an animal or shell.


producing living young instead of eggs from within the body in the manner of nearly all mammals, many reptiles, and a few fishes
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- Y -

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- Z -


single-cell dinoflagellate (golden-brown) algae living symbiotically within the cells of some cnidarians (members of phylum Cnidaria or Coelenterata; includes radially symmetrical ocean animals such as sea anemones, corals, hydroids, and jellyfish)

type of plankton composed of small animals; mainly small crustaceans and fish larvae
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Revised: Dec 1, 2008.
Copyright 1997-2009  by Jeffrey Jeffords.
All trademarks or product names mentioned herein are the property of their respective owners.