Introductory Terms Flashcards
Biradial symmetry
A combination of radial and bilateral symmetry, as in the Ctenophores. Here, the body components are arranged with similar parts on either side of a central axis, and each of the four sides of the body is identical to the opposite side but different from the adjacent side.
Radial Symmetry
a basic body plan in which the organism can be divided into similar halves by passing a plane at any angle along a central axis, characteristic of sessile and bottom-dwelling animals, as the sea anemone and starfish.
Bilateral symmetry
a basic body plan in which the left and right sides of the organism can be divided into approximate mirror images of each other along the midline.
Dorsal
situated on or toward the posterior plane in humans or toward the upper plane in quadrupeds.
Ventral
situated on or toward the lower, abdominal plane of the body; equivalent to the front, or anterior, in humans.
anterior
pertaining to or toward the head or forward end of the body.
Posterior
pertaining to or toward the rear or caudal end of the body.
Lateral
Of or pertaining to the side; situated at, proceeding from, or directed to a side
Medial
situated in or pertaining to the middle; median; intermediate.
Reynolds number
a dimensionless number, v ρ l /η, where v is the fluid velocity, ρ the density, η the viscosity and l a dimension of the system. The value of the number indicates the type of fluid flow
Cilia
minute hairlike organelles, identical in structure to flagella, that line the surfaces of certain cells and beat in rhythmic waves, providing locomotion to ciliate protozoans and moving liquids along internal epithelial tissue in animals.
flagella
a long, lashlike appendage serving as an organ of locomotion in protozoa, sperm cells, etc.
hydrostatic skeleton
A structure found in many cold-blooded organisms and soft-bodied animals consisting of a fluid-filled cavity, the coelom, surrounded by muscles. The pressure of the fluid and action of the surrounding circular, longitudinal, and/or helical muscles are used to change an organism’s shape and produce movement, such as burrowing or swimming.
exoskeleton
an external covering or integument, especially when hard, as the shells of crustaceans
endoskeleton
the internal skeleton or framework of the body of an animal
sagittal plane
a vertical plane which passes from ventral (front) to dorsal (rear) dividing the body into right and left halves
frontal plane
A plane parallel to the long axis of the body and perpendicular to the sagittal plane that separates the body into front and back portions.
transverse plane
plane that divides the body into superior and inferior parts. It is perpendicular to the coronal and sagittal planes.
Bilateria
All animals having a bilateral symmetry, i.e. they have a front and a back end, as well as an upside and downside.
enterocoely
process by which some animal embryos develop in which a mesoderm is formed in a developing embryo, in which the coelom forms from pouches “pinched” off of the digestive tract (also known as the embryonic gut, or archenteron)
schizocoely
A process by which some animal embryos develop. Animals which develop through schizocoely are known as schizocoelomates. Schizocoely occurs when a coelom (body cavity) is formed by splitting the mesodermal embryonic tissue.
Pseudocoel
An internal body cavity of some primitive invertebrates, similar to a coelom but lacking a mesodermal lining.
Coelom
the body cavity of many multicellular animals, situated in the mesoderm and containing the digestive tract and other visceral organs
radial cleavage
holoblastic cleavage that is typical of deuterostomes and that is characterized by arrangement of the blastomeres of each upper tier directly over those of the next lower tier resulting in radial symmetry around the pole to pole axis of the embryo
spiral cleavage
holoblastic cleavage that is typical of protostomes and that is characterized by arrangement of the blastomeres of each upper tier over the cell junctions of the next lower tier so that the blastomeres spiral around the pole to pole axis of the embryo
blastula
an early embryonic form produced by cleavage of a fertilized ovum and consisting of a spherical layer of cells surrounding a fluid-filled cavity.
Blastocoel
The fluid-filled, central cavity of a blastula. Also called segmentation cavity.
Gastrula
An embryo at the stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates with the exterior through the blastopore.
Gastrulation
the process in which a gastrula develops from a blastula by the inward migration of cells
Germ layers
each of the three layers of cells (ectoderm, mesoderm, and endoderm) that are formed in the early embryo.
Endoderm
the innermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the lining of the gut and associated structures.
Ectoderm
the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue.
Mesoderm
the middle layer of an embryo in early development, between the endoderm and ectoderm.
Diploblastic
having a body derived from only two embryonic cell layers (ectoderm and endoderm, but no mesoderm), as in sponges and coelenterates.
Triploblastic
having a body derived from three embryonic cell layers (ectoderm, mesoderm, and endoderm), as in all multicellular animals except sponges and coelenterates
Larvae
the active immature form of an insect, esp. one that differs greatly from the adult and forms the stage between egg and pupa, e.g., a caterpillar or grub.
Indirect development
biologic development accompanied by a metamorphosis
Settlement
a place, typically one that has hitherto been uninhabited, where people establish a community.
Metamorphosis
a major change in the form or structure of some animals or insects that happens as the animal or insect becomes an adult
Epidermis
The outer, protective, nonvascular layer of the skin of vertebrates, covering the dermis.
Epithelium
Membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs.
Cuticle
The noncellular, hardened or membranous protective covering of many invertebrates, such as the transparent membrane that covers annelids.
Nephridia
(in many invertebrate animals) a tubule open to the exterior that acts as an organ of excretion or osmoregulation. It typically has ciliated or flagellated cells and absorptive walls.
Protonephridia
A hollow cell in the excretory system of certain invertebrates, including flatworms and rotifers, containing a tuft of rapidly beating cilia that serve to propel waste products into excretory tubules.
Metanephridia
excretory organs in invertebrates (mainly annelids), paired metameric tubules of ectodermal origin that open at one end through a ciliated funnel into the coelomic sacs (the secondary body cavity) and at the other end to the exterior. Developed evolutionarily from protonephridia.
blood vascular system
The tissues and organs of an animal that transport blood through the body. In vertebrates it consists of the heart and blood vessels
haemocoel
The body cavity in between organs whereby the hemolymph circulates through.In most vertebrates the oxygen is supplied to different organs of the body through capillaries in a closed circulatory system. In many invertebrates, the oxygen is supplied directly to the organs. That is, the hemolymph circulates through this and bathes the organs directly to supply them with oxygen.
open circulatory system
Circulatory system that is common to molluscs and arthropods. It pumps blood into a hemocoel with the blood diffusing back to the circulatory system between cells. Blood is pumped by a heart into the body cavities, where tissues are surrounded by the blood.
closed circulatory system
Vertebrates, and a few invertebrates, have a ______circulatory system. They have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities.
Respiratory pigments
any of various permanently or intermittently colored conjugated proteins and especially hemoglobin that function in the transfer of oxygen in cellular respiration
Photoreceptor
a light-sensitive cell or organ that conveys impulses through the sensory neuron connected to it
chemoreceptor
A sensory nerve cell or sense organ, as of smell or taste, that responds to chemical stimuli.
Mechanoreceptor
A specialized sensory end organ that responds to mechanical stimuli such as tension, pressure, or displacement.
Statocyst
A small organ of balance in many invertebrates, consisting of a fluid-filled sac containing statoliths that stimulate sensory cells and help indicate position when the animal moves. Also called otocyst.
Statolith
Any of the granules of calcium carbonate occurring in a statocyst: movement of ________, caused by a change in position of the animal, stimulates hair cells, which convey the information to the brain by nerve fibres
Clone
an organism or cell, or group of organisms or cells, produced asexually from one ancestor or stock, to which they are genetically identical.
Coloniality/colony
Refers to individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defense or the ability to attack bigger. Colonial organisms were probably the first step toward multicellular organisms via natural selection
broadcast spawning
animals release their eggs and sperm into the water, where fertilization occurs externally. Common in mollusks and other invertebrates
internal fertilization
union of the gametes inside the body of the female, the sperm having been transferred from the body of the male by an accessory sex organ or other means.
seminal vesicle
Either of a pair of pouchlike glands situated on each side of the male urinary bladder that secrete seminal fluid and nourish and promote the movement of spermatozoa through the urethra.
seminal receptacle
A container that is used to hold semen. It is where the sperm is received in an earthworm.
Gonoduct
a duct leading from a gonad to the exterior, through which gametes pass
oviduct
the tube through which an ovum or egg passes from an ovary.
sperm duct
The vas deferens, also called ductus deferens, is part of the male anatomy of many vertebrates; they transport sperm from the epididymis in anticipation of ejaculation.
gonochoristic
describes the state of having just one of at least two distinct sexes in any one individual organism.
dioecious
having the male and female reproductive organs in separate individuals.
hermaphroditic
an organism, as an earthworm or plant, having normally both the male and female organs of generation.
monoecious
having both the male and female reproductive organs in the same individual; hermaphrodite.
protandry
(of hermaphrodite animals) producing male gametes before female gametes.
protogyny
a state in hermaphroditic systems that is characterized by development of female organs or maturation of their products before the appearance of the corresponding male product thus inhibiting self-fertilization and that is encountered in apples, pears, figworts, and among several groups of invertebrate animals
parthenogenesis
A form of reproduction in which an unfertilized egg develops into a new individual, occurring commonly among insects and certain other arthropods.
benthic
of, relating to, or occurring at the bottom of a body of water
pelagic
Of, relating to, or living in open oceans or seas rather than waters adjacent to land or inland waters
epifauna(l)
Benthic animals that live on the surface of a substrate, such as rocks, pilings, marine vegetation, or the sea or lake floor itself.
infauna(l)
Aquatic animals that live in the substrate of a body of water, especially in a soft sea bottom.
sessile
the inability to move actively or spontaneously
errant
(of a polychaete worm) of a predatory kind that moves about actively and is not confined to a tube or burrow.
plankton(ic)
the small and microscopic organisms drifting or floating in the sea or fresh water, consisting chiefly of diatoms, protozoans, small crustaceans, and the eggs and larval stages of larger animals. Many animals are adapted to feed on them esp. by filtering the water.
holoplanktonic
Plankton that remains free-swimming through all stages of its life cycle.
meroplanktonic
Any of various organisms that spend part of their life cycle, usually the larval or egg stages, as plankton.
symbiosis
interaction between two different organisms living in close physical association, typically to the advantage of both.
parasite/parasitism
an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host’s expense.
suspension feeding
Type of feeding common in an aquatic animal, such as a clam, barnacle, or sponge, that feeds by filtering particulate organic material from water.
deposit feeding
Feeding practiced by an aquatic animal that feeds on small specks of organic matter that have drifted down through the water and settled on the bottom.
synonym
A scientific name that applies to a taxon that goes by a different scientific name, although zoologists use the term somewhat differentlyIn scientific nomenclature, a synonym is a scientific name that applies to a taxon that goes by a different scientific name, although zoologists use the term somewhat differently
monophyletic
a taxon that is defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendants
paraphyletic
a taxon defined as one that includes the most recent common ancestor, but not all of its descendants
polyphyletic
a taxon that does not include the common ancestor of all members of the taxon
homology
a fundamental similarity based on common descent
homoplasy
correspondence between parts or organs acquired as the result of parallel evolution or convergence
clade
A grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor. Imagine clipping a single branch off the phylogeny.
plesiomorphy
An ancestral or primitive character.
symplesiomorphy
A character shared by a number of groups, but inherited from ancestors older than the last common ancestor.
apomorphy
A derived or specialised character.
synapomorphy
An apomorphy (derived or specialised character) shared by two or more groups which originated in their last common ancestor.
sister taxa
a systematic term from cladistics denoting the closest relatives of a group in a phylogenetic tree.
category vs. taxon
category: The name given to various taxonomic ranks. ex: Kingdom, Phylum, Class, Order, Family, Genus species–> these are categories
taxon: the group of organisms occupying a particular taxonomic rank
character vs. character state
-character: Any heritable attribute or feature of an organism that can be used for recognizing, differentiating or classifying a taxon.
Biologists use characters from a variety of different sources, including morphological, behaviorial, developmental, and molecular data.
-character state: Alternative forms of a character.
grade
refers to a taxon united by a level of morphological or physiological complexity.
Precambrian
the time period from the beginning of Earth, about 4.5 billion years ago, to the beginning of the Paleozoic era, about 543 million years ago.
Paleozoic
this era spans the time from the end of the Precambrian, about 543 million years ago, to the beginning of the Mesozoic, about 248 million years ago. It is generally subdivided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.
Mesozoic
spans the time from the end of the Paleozoic, about 248 million years ago, to the beginning of the Cenozoic, about 65 million years ago. It is generally subdivided into three periods: Triassic, Jurassic, and Cretaceous.
Cenozoic
spans the time from the end of the Mesozoic, about 65 million years ago, to the present. It is generally subdivided into two periods, the Tertiary and the Quaternary.
