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Tree of Life - Nature glossary Category: Animals and Nature > Natural life Date & country: 25/01/2014, USA Words: 214

M
Resemblance among several unpalatable/vigilant species.

xenosome (xenosomes)
A foreign body. Used to refer both to bits of debris which may be incorporated into the shells of some testate amoebae, and also to symbiotic algae lying inside other cells. Probably best restricted to the first use.

vacuole (vacuoles)
A structure in a cell enclosed by a membrane. Usually food vacuoles (associated with the digestion of food) or contractile vacuoles (association with the excretion of fluid). Small vacuoles may be called vesicles.

trophic
Said of organisms which are active and feeding, and contrasts with the encysted state, theronts, or swarmers. May also be used to refer to those aspects of metabolism associated with growth

undulipodium (undulipodia)
A term preferred by some workers, usually in the US, for eukaryotic cilia and flagella.

unicellular
Consisting of but a single cell.

theront
A form adopted by some species of ciliates that typically does not feed but moves quickly. May be thought of as an adaptation in response to a lack of food and the task of which is to hunt out new sources of food.

trichocyst
A type of extrusome which, when extruded, takes the form of a fine stiff filament. Typical of Paramecium, but used inadvertently to refer to other types of extrusomes.

terrestrial
Pertaining to land - as opposed to the water (aquatic) or the air (aerial).

tetrasporangium (tetrasporangia)
A unicellular sporangium containing four asexual tetraspores which are produced from meiosis. Tetrasporangia are found in certain red algae.

theca
A layer which encloses a body, may refer to a closely adpressed rigid wall, or to a more loosely-attached rigid lorica or test or even to a soft enclosing sheath of material.

terminal taxon (terminal taxa)
The taxa or named groups at the tips of the branches of a tree.

tendril (tendrils)
A slender climbing organ by which some twining plants attach themselves to an object for support, formed by modification of a part of a plant, e.g. a stem, a leaf or leaflet, a stipule.

taxon (taxa)
Any named group of organisms.

sympatry (sympatric)
Species or populations occupying the same geographic area. Compare to allopatry.

sterile
Incapable of reproduction.

stomatocyst (stomatocysts)
A type of cyst, with a siliceous wall and a single plugged opening, formed by some chrysomonads (stramenopiles).

suspension feeding
Feeding on suspended particles. The most usual ploy is filter-feeding, but not all suspension feeders feed in this way.

stamen (staminate, stamens)
The male reproductive organs of a flower. They produce pollen and usually consist of slender, thread-like stalks (filaments) topped by pollen-bearing anthers.

standard length (SL)
The length of a fish measured from the tip of the snout to the end of the fleshy part of the body. This measurement is preferred by many ichthyologists because it ignores the tail fin, which can often be damaged in specimens.

starch grain (starch grains)
A term used loosely to refer to refractile masses of polysaccharides which are accumulated as storage products in the cell.

sporulation
The process of spore development.

sporangiophore
A stalk bearing one or more sporangia.

spore (spores)
Unicellular body produced by plants, fungi, and some microorganisms. Often a resting stage, encased in a protective coat, adapted to resist heat, desiccation, or other unfavorable environmental conditions. Spores can give rise to a new individual either directly or after fusion with another spore.

sporophyte (sporophytes)
The phase of the life cycle of sexually reproducing plants and algae in which the spores are produced. The sporophyte arises from the diploid zygote.

sessile
Refers to organisms which are fixed to the substrate, for example by means of a stalk or lorica.

siliceous
Incoporating silica.

spasmoneme
A contractile element in the stalk of some peritrich ciliates.

spicule (spicules)
Delicate pointed structures lying external to the body and usually pointed away from it. Like spines, but invariably excreted and more delicate.

sporangiferous
having sporangia

sepal (sepals)
The leaf-like, outermost organs of a flower. They are sterile and protect the fertile parts of the developing flower.

septicidal
When a fruit capsule dehisces along lines coinciding with the partitions between loculi (the enclosed compartments within the ovary). Compare loculicidal.

sequence alignment
Procedure for the linear comparison of two or more molecular sequences in order to identify those positions that are likely to have a common evolutionary origin. Series of characters that are in the same order in the sequences are used as reference points, and hypothetical gaps may be inserted in order to make similar regions line up with one another.

rheotaxis (rheotactic)
Movement of an organism in response to the motion of a current of water or air.

rheotropism (rheotropic)
Growth or orientation of an organism, or of part of an organism, in response to the motion of a current of water or air.

RNA (ribonucleic acid)
A molecule found in the nucleus and cytoplasm of cells. It plays an important role in protein synthesis and other chemical processes of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.

reversal (character reversal)
The re-establishment of an ancestral character state through the loss of an evolutionary novelty (apomorphy). For example, winged insects (Pterygota) evolved from a wingless ancestor; however, some pterygote lineages have subsequently lost their wings, e.g., fleas, lice, some grasshoppers and beetles.

pyrenoid (pyrenoids)
A protein body lying inside some types of chloroplasts.

pusule
A system involving a sac and channels and found in some dinoflagellates. The function is not understood, but it may act as an osmoregulatory organelle.

punctate
With a dimpled or spotted appearance.

protist (Protista, protists)
A paraphyletic group consisting of those eukaryotes which are not animals, true fungi or green plants.

protozoan (Protozoa, protozoans)
From a phylogenetic point of view, an outmoded concept because it included unrelated eukaryotes - various amoebae, flagellates, ciliates and sporozoa

proximal
Near to (compare distal).

pseudopodium (pseudopodia)
Transient extensions of the cell surface, used for locomotion or feeding. They may be supported internally (actinopods) or not (rhizopoda), they may be thread like (filose) or broad (lobose), may or may not bear extrusomes (nudipodia, extrusopodia) and they may be one (monopodial) to many (polypodial) produced at one time.

polytomous tree
A tree that has at least one branch point that is a polytomy. A tree with only one polytomy is called polytomous, as is a tree with multiple polytomies. This is in contrast to a dichotomous tree.

polytomy (polytomies)
A branch point on a tree that has more than two immediate descendents.

protein (proteins)
A large molecule composed of amino acid chains. Proteins perform a wide variety of cellular functions. Examples are hormones, enzymes, and antibodies.

plasmodium (plasmodia)
A type of amoeboid organization involving a large mass of cytoplasm and, usually, many nuclei. A type of body form adopted by some slime moulds. The genus Plasmodium is the cause of malaria.

polypeptide (polypeptides)
A chain of amino acids, usually less than 100 amino acids in length. Polypeptides are the building blocks of proteins.

polyphyletic
A group of organisms that does not include their most recent common ancestor. (cf. monophyletic; technically speaking, the distinction between polyphyletic and paraphyletic is not as clear as it might seem.)

plankton (planktonic)
Organisms living in the water column (above the sediment).

pinocytosis
A process of ingesting material by enclosing it with a membrane. The resulting structure is usually too small to be seen with the light microscope and is mostly suitable for the ingestion of fluid or mucus.

phylogenetics
The scientific discipline of resolving phylogenetic relationships between organisms.

phylogenetic inference
The scientific process of collecting and analyzing data to provide the best estimate of the true phylogeny of a group of organisms.

photosynthesis
A means of acquiring energy for metabolism which involves trapping radiant energy in chloroplasts, the use of that energy to break up water molecules (hydrolysis) and to convert released energy into an accessible form - such as the molecule ATP. The only form of autotrophy in eukaryotic cells. Some heterotrophic protists have symbiotic algae which allow them to exploit photosynthesis.

photosynthetic pigments
Large molecules in chloroplasts that absorb radiant energy (hence they have colour), mostly chlorophylls and carotenes and, occasionally phycobilins.

phagotroph
An organism which feeds by phagocytosis.

pharynx
A region of the ingestion apparatus lying internal to the mouth (of a metazoan organism) or internal to the cytostome of a protist. Involved in the swallowing process (see cytopharynx).

photic (photic zone)
The upper zone of a body of water (a lake or an ocean) that is penetrated by sufficient sunlight to allow for photosynthesis.

photosynthates
The products of photosynthesis.

phagocytosis
The ingestion of visible particles of food by enclosing them with a membrane to form a food vacuole.

petal (petals)
The most conspicuous organs of a flower, often brightly colored, providing chemical and visual signals as well as landing platforms for pollinators. They are sterile and surround the fertile organs.

periplast
The entire assemblage of scales, spines and spicules which encase some heliozoa, chrysomonads, etc.

peristalsis
Regular contractions of a body or part of a body. Mostly said of the intestinal system of vertebrates but also the squirming behaviour of some euglenids.

peristome
The region of the body around, and external to, the mouth. To deserve application of this term, the region must be modified to favour the acquisition of food.

pelagic
Pertaining to the water column of the open sea - as opposed to coastal areas or the sea floor.

pellicle
The outer region of cytoplasm of some protozoa, the term is applied only when the region can be distinguished because it appears to be relatively stiff and highly structured. Used mostly in reference to euglenids and ciliates.

paraxial rod
A rod of material lying within the flagellum parallel to the axoneme, only found in some protists (e.g. euglenids) causing the flagellum to appear relatively thick.

parasitoid (parasitoids)
An organism that is parasitic on a single host in its immature stages, usually kills its host at some point during its development, and is free-living as an adult. Most known parasitoids are insects, in particular wasps (Ichneumonidae, Chalcidae), flies (Tachinidae), and strepsipterans (Stylopidae).

outgroup (outgroups)
A taxon that is not part of the ingroup but that is included in a phylogenetic analysis in order to provide information about the root of the ingroup and to help differentiate between apomorphies and plesiomorphies in the ingroup.

ovipositor (ovipositors)
A tubular organ that is used for oviposition, i. e., the laying of eggs. In some insects, especially parasitoid wasps, the ovipositor can be very long.

paraphyletic (paraphyly)
A group of organisms that includes their most recent common ancestor and some but not all of its descendents. (cf. monophyletic; technically speaking, the distinction between polyphyletic and paraphyletic is not as clear as it might seem.)

nudipodium (nudipodia)
A type of unsupported pseudopodium without evident extrusomes (compare extrusopodia).

organelle (organelles)
A discrete structure found within eukaryotic cells.

organism (organismal, organisms)
Any living creature. A plant, animal, or micro-organism.

osmotrophic
A form of nutrition in which soluble compounds are taken up by the organism, either by pinocytosis or by mechanisms capable of transporting one or a few molecules at a time (membrane pumps).

nucleus (nuclei)
An organelle found only in eukaryotic cells, in which most of the cellular DNA (genetic material) is located. Most cells have a single nucleus, but certain species may have many nuclei.

nucleotide (nucleotides)
Molecule that serves as the basic structural unit of nucleic acids like DNA and RNA. Each nucleotide consists of three other molecules

nucleolus (nucleoli)
An optically dense region (or regions) in a nucleus, associated with RNA synthesis. Not always visible.

nucleated
Having a nucleus.

neuston (neustonic)
The environment of the interface between water and air, often rich in bacteria and protists.

nocturnal
An organism that is active at night rather than during the day.

node (nodes)
A branching point in a phylogenetic tree, representing the common ancestor of the lineages descending from this branching point.

neritic
A term referring to ocean waters from the low-tide mark to the edge of the continental shelf at a depth of about 200 meters. The neritic zone is characterized by low water pressure, plenty of sunlight, and stable temperatures.

mucus
A gelly-like substance produced by organisms, texture may vary from virtually fluid to stiff and rubber-like.

multicellular
An organism consisting of more than one cell.

nemadesmata
Stiff aggregates of many microtubules found around the cytostome of some ciliates and used during the ingestion of food. A type of ingestion rod.

mucilaginous
Made of, or with the texture of, mucus

motile
Moving, for example by swimming, gliding, crawling, jumping, or kicking. Part of the body (e.g., cilia) may be motile in a cell which is not motile and is fixed in one position.

mimicry (mimic)
Resemblance of an organism (the mimic) in appearance and/or behavior to another organism or object (the model).

mixotrophic
Used in reference to organisms which use a mixture of nutritional strategies, such as organisms with chloroplasts and carry out photosynthesis but are also able to feed by phagocytosis.

monophyletic (monophyly)
A group of organisms that includes their most recent common ancestor and all of its descendents. (cf. paraphyletic, polyphyletic)

morphology (morphological)
The study of the form and structure of an organism or one of its body parts. The word is sometimes used to also mean the form or structure itself.

microtubule (microtubules)
A subcellular structure comprised of the protein tubulin and used for support - part of the cytoskeleton. Individual microtubules cannot be seen by conventional light-microscopy, but aggregates of microtubules can.

marine
Pertaining to the sea.

mastigophore
Projection of a cell that supports one or more flagella

membranelle
A compound structure comprised of many cilia and associated with the mouth of a ciliate. Either present in groups of three (oligohymenophora) or as a band of many more (polyhymenophora).

micronucleus (micronuclei)
One of two kinds of nuclei found in ciliates, dividing to produce two similar nuclei during asexual reproduction and producing nuclei with half the complement of dna for sexual activity. usuaully the smaller of the two types of nuclei, but many may be present. some cells lack a micronucleus and survive quite well without it.

loculicidal
When a fruit capsule dehisces along lines coinciding with the centers of loculi (the enclosed compartments within the ovary). Compare septicidal.

lorica
An organic or inorganic casing or shell incompletely surrounding an organism, usually loose fitting.