Class Notes (835,674)
Canada (509,327)
Biology (2,930)
BIO1130 (713)
Jon Houseman (558)

bio key terms part 3.docx

32 Pages
Unlock Document

Jon Houseman

Cambrian and Ordivicianacoelomate Triploblastic animals phylum Platyhelminthes that do not have an internal body cavity that separates the gut from the muscles of the body Instead they have a mass of cells derived largely from mesoderm that packs the region between the gut and the body wall Although this term could be applied to other lower phyla it is most accurately used with the triploblasts rather than diploblastsAlgal mats Prior to the start of the Cambrian the ocean bottom is believed to be covered by impenetrable algal mats and one of the innovative feeding strategies of the Cambrian was being able to penetrate the mats and feed on the substrate underneath There was an explosion of these soft bodied burrowers which is independent of mineral based fossilization This would suggest that the explosion may have been realAmebocyte the large macrophagelike amoeboid cells in the mesohyl that are totipotent and can differentiate into any other type of sponge cell are also phagocytic and play a role in digestion and internal transportArchenteron The name given to the primitive gut the first tube that runs through the developing embryo and is open to the external environment Formed during gastrulation it is surrounded by the new endoderm and it will develop into the digestive system of the organismArcheocyteCell capable of a variety of functions or of differentiating into a variety of cell types with different functions Examples include the wandering amebocytes in the mesohyl of a spongeBivalve Bivalvia is a class of marine and freshwatermolluscs with laterally compressed bodies enclosed by a shell in two hinged parts Bivalvesinclude clams oysters mussels scallops and numerous other families of shells The majority are filter feeders and have no head or radula Thegills have evolved into ctenidia specialised organs for feeding and breathing Most bivalves bury themselves in sediment on the seabed where they are safe from predation Others lie on the sea floor or attach themselves to rocks or other hard surfaces A few bore into wood clay or stone and live inside these substances Some bivalves such as the scallops can swimBlastopore The opening to the primitive gut archenteron that will develop into either the mouth or anus The blastopore forms during gastrulation Blastula a hollow cavity found during cell division when the cells form a ball shape A stage in the development of multicellular animals in which only one cell layer is present the blastoderm the cavity the cells surround is the blastocoel The embryo resembles a hollow ball Bryozoa A phylum of aquatic mainly marine invertebrates comprising the moss animals and sea mats Bryozoans live in colonies 50 cm or more across which are attached to rocks seaweeds or shells The individuals zooids making up the colonies are about 1 mm long and superficially resemble cnidarian polyps with a mouth surrounded by ciliated tentacles of the lophophore that trap minute particles of organic matter in the water Some have a horny or calcareous outer skeleton into which the body can be withdrawn Bryozoans are placed in the clade of protostome animals called the LophotrochozoaCambrian The first period in the Paleozoic Era of the Phanerozoic Eon It is the longest period in this eon as it lasts over 120 million years from 550488 million years ago The Early Cambrian had ideal conditions for flourishing biodiversity such asthe rapid development of marine fauna and an explosion in the appearance of new forms of animals particularly in the warm and shallow seas bordering continents Cambrian explosion This explosion is known as the Cambrian Explosion or Evolutions Big Bang due to the rapid rate of evolution of several body plans in soft bodied invertebrate animals The Cambrian Period marked a profound change in life on Earth prior to the Cambrian living organisms on the whole were small unicellular and simple Complex multicellular organisms gradually became more common in the millions of years immediately preceding the Cambrian but it was not until this period that mineralizedhence readily fossilizedorganisms became common The rapid diversification of lifeforms in the Cambrian known as the Cambrian explosion produced the first representatives of many modern phyla representing the evolutionary stems of modern groups of species such as the molluscs and arthropodsBurgess Shale fossils Evidence for the Cambrian Explosion arose from the fossils of the soft bodied invertebrates fossilized in the Burgess Shales in Yoho National Park BC This areawas at the edge of the continent Laurentia during the Cambrian EraBefore their discovery the fossil record was seen as incomplete as we had no fossils of soft bodied invertebrates and they were thought as incapable of fossilizingHowever 505 million years ago a series of mudslides carried the animals that lived at the edge of a submarine cliff the Cathedral Escarpment over its edge and buried them in fine silt That mud and its contained fossils formed shale a sedimentary rock with layers that are easily split apart We are able to bisect these fossils and completely analyze the animals that are preserved within them Predators An animal that obtains its food by predation All predators are carnivores although not all carnivores are predators Cambrian burrowers Burrow vertically unlike fossils of ediacaran burrowers who burrowed horizontally Cambrian swimmers Carnivores Any animal that eats other animals as its only source of food L carni fleshvorare to eat An animal that eats meat especially a member of the order Carnivora eg tigers wolves Carnivores are specialized by having strong powerful jaws and welldeveloped canine teeth They may be predators or carrion eatersCephalopodThe most advanced class of molluscs containing the squids cuttlefishes octopuses and the extinctammonites Cephalopods have a highly concentrated central nervous system within a protective cartilaginous case The eye has a welldeveloped retina and is comparable to that of vertebrates All cephalopods are predacious carnivores capable of swimming by jet propulsion they have highly mobile tentacles for catching and holding preyChoanocyte The common ancestor to all animals is the colonial choanocyte A choanocyte cell consists of a cell body and a set of microvilli arranged in a circle with a flagellum extending from inside the microvilli circle When the flagellum beats it creates a current that drives water through the microvilli and out As the water passes through the microvilli consume any large particles by phagocytosis giving the cell nutrients Choanoflagellate Choanoflagellata 150 species are not a diverse group of protists They are small singlecelled protists found in both fresh waters and the oceans taking their name collarflagellates from the circle of closely packed microvilli or slender fingerlike projections that surrounds the single flagellum by which choanoflagellates both move and take in food The microvilli are so closely packed that under light microscopy the collar appears as a single transparent unit as it does in these drawings As the flagellum beats it draws water through the microvilli in the collar which filter out bacteria and other tiny food particles The flagellum may push the cell forward in the case of freeswimming choanoflagellates many species however are attached to a substrate by a thin stalk for part or all of their life cycles They reproduce by simple division and sex is unknown yet their life cycles are not yet thoroughly studiedChoanoflagellates have no fossil record although some marine species secrete delicate loricae or outer coverings made of fine interwoven silica bars Though delicate such loricae could conceivably be preserved as fossils Yet choanoflagellates must have existed on the Earth since the Late Precambrian because they are the closest living protist relatives of the sponges the most primitive metazoans Choanoflagellates are almost identical in shape and function with the choanocytes or collar cells of sponges these cells generate a current that draws water and food particles through the body of a sponge and they filter out food particles with their microvilli Choanoflagellatelike cells are also found in other animal phyla in organisms such as flatworms and rotifers for instance choanoflagellatelike cells are found in flame bulbs that act as excretory organs A few living choanoflagellates such as Proterospongia are colonial for part of their life cycle and show a limited degree of cell differentiation and integration into a unit these colonial choanoflagellates are the best living examples of what the ancestor of all metazoans may have looked likeColonial choanoflagellate A collection colony of choanocyte cells can pump more water collectively than an individual cell trapping more nutrients producing more cells increasing fitness of the colony However this is a colonial system as all cells perform the same function Ancestor to animals and fungi Choanoderm The choanocyte lining on the inside of a sponge A monolayer of choanocytes lining the spongocoel of a sponge a type of epithelioid tissueCnidaria cnidarians are the first animals to have tissues derived from endoderm and ectoderm formed during gastrulation Both are epithelial The ectoderm lines the outside of the body and the endoderm lines the digestive tract Cnidarians are predatory and use stinging cells cnidocytes to capture their prey Cnidocil A modified flagellum on the cnidocyte that causes the nematocyst inside to fire The stimulus involves some sort of chemical cue touching the cnidocil doesnt fire the nematocystCnidocyte Cnidocytes give the phylum its name and are embedded in the epidermis around the mouth and when present the tentacles or arms The secret to how they work is the cells specialized organelle the cnida and inside it the deadly barbed sticky or poisontipped thread waiting to be fired if the cells cnidocil is triggeredThe nematocyst is the most common form of a cnidocyte and like all cnidocytes once it is fired it cant be used again and a new cnidocyte formsCoelom formation Can either form through schizocoely or enterocoely During schizocoely mesoderm forms from cells near the blastopore that proliferate between the endoderm that forms during gastrulation and the outer ectoderm As the mesoderm expands it splits and the opening in the mesoderm becomes the coelom Schizocoely gets its name from the splitting of the mesoderm Coelomate The body plan of many bilaterally symmetrical animals includes a body cavity that separates the gut from the muscles of the body wall Coelomate animals have a coelom a fluidfilled body cavity completely lined by the mesodermThe counterpart to schizocoely is enterocoely where the mesodermal cells form from the endoderm of the primitive gut that forms during gastrulation and was once considered a synapomorphy for the deuterostomesCorals A structure made from the hard skeletons of coral animals or polyps found largely in tropical and subtropical marine environments Any of a group of sedentary colonial marine invertebrates belonging to the class Anthozoa of the phylumCnidaria A coral colony consists of individual polyps within a protective skeleton that they secrete this skeleton may be soft and jellylike horny or stony The horny skeleton secreted by corals of the genus Corallium especially C rubrum constitutes the red or precious coral used as a gemstone The skeleton of stony or true corals consists of almost pure calcium carbonate and forms the coral reefs common in tropical seasDeposit Substrate feeders An animal that consumes particles of organic matter from the solid substrate on which it livesDeuterostome Phyla including the Chordata and Echinodermata that share common characteristics of the blastoporenot forming the mouth radial indeterminate cellular cleavage in the embryo and the formation of the body cavity by enterocoelic pouching Gr deuteros secondstoma mouth An animal in which the opening blastopore of the embryonic cavity see ARCHENTERON becomes the anus and the mouth forms as a secondary orifice The name derives from Greek meaning literally second mouth Deuterostomes comprise one of the two main subkingdoms of animals Deuterostomia the other being the Protostomia see PROTOSTOME Deuterostomes typically display radial cleavage of the blastula indeterminate development the fate of cells is not established until later stages of development and enterocoelic formation of the coelom ie by outpocketing of the embryonic gut The three deuterostome phyla are the HemichordataEchinodermata and Chordata A division of the
More Less

Related notes for BIO1130

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.