Integrity of Benthic Macroinvertebrate Communities in

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The gut narrows where it passes through the head–trunk septum, and it extends posteriorly as a long intestine. The concentration of oxygen in dry air at sea level is uni- formly about 210 ml/liter, whereas in water it ranges from near zero to about 10 ml/liter. Giardia lamblia is a cosmopolitan species that occurs most commonly in warm climates. For example, the long-recognized group Reptilia is cer- tainly paraphyletic because it excludes one of that group’s most distinct lineages, the birds.

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Copepoda: Developments in Ecology, Biology and Systematics:

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In primitive archaeo- gastropods (e.g., keyhole limpets, abalones, top shells), the radulae bear large numbers of fine marginal teeth in PHYLUM MOLLUSCA 33UNCORRECTED PAGE PROOFS Figure 20.23 A generalized molluscan radula and asso- ciated buccal structures (longitudinal section). Molecular phylogeny of the animal kingdom. In this lesson, we will learn how to distinguish between vertebrates and invertebrates. A binocular microscope with a 20X magnification is advisable for those wishing to view living and preserved specimens.� Greater detail on a particular group or species may be found by referring to publications listed in the Bibliography or through Internet searches. ��������� This is a self-contained database with a minimum of links outside its limits.� Independent Internet searches are encouraged for greater detail on a particular animal group. ����������� The above differ also in their nuclear content.� Foraminifer and Radiolara use asexual reproduction.� Flagella also occur in the Sarcodina.� There are many that form symbiosis with algae.� For example, Zoochlorellae are Heliozoa with green algae; Zooxanthellae are Radiolaria with yellow algae. ��������� Their importance ranks high.� Endomoeba histolytica is a notorious intestinal parasite and they serve as an important link in the food chain. ��������� The Protista that have been called Protozoa, or " First Animals " are more like the early primitive animals than any other living forms.� They have changed less than other groups.� They are usually single-celled animals that may exit in a colony.�� But each individual cell retains its independence.� Their simplicity is often deceiving.� Amoebe, for instance, do all the basic functions as humans.� However, the cells of Protozoa are so complex that they have frequently been regarded as "acellular."� There are all grades of cellular differentiation from very primitive as in amoeba and advanced as in the higher ciliates and flagellates.� There are definite openings for the taking of food developed.� Locomotor structures appear and contractile structures show up, which function as muscle fibers.� The bases of the cilia and flagellae are connected.� Different grades of reproduction occur from binary fission, complete sexual differentiation and an alternation of sexual generations.� Protista have reached the point of multicellular organization.� Flagellates are shown to be the most developed and it is believed that they resemble the original stock group that gave rise to both plants and animals.� At one time all Protista were believed to have evolved from the flagellates. ��������� The Class Rhizopoda (Sarcodina) is characterized by pseudopodia, which are organelles that are not true organs.� They serve in locomotion and food getting.� The cytoplasm of the cell is not provided with many visible structures that possess specific functions.� Amoeba proteus is a common fresh water rhizopod that occurs in calm, semi-stagnant water.� It is microscopic in size and its form is indefinite. ��������� Ingestion & Digestion of Food .-- The cytoplasm of A. proteus consists of two parts:� (1) a plasmagel that includes a clear layer and an outer portion of endoplasm, and (2) a plasmasol, which is a fluid or the inner endoplasm.� The organism is holozoic, taking in solid food consisting of algae (diatoms) and other protozoa into its body.� The food is captured by the pseudopodia, and a food cup is formed that engulfs the food bringing it inside in a food vacuole.� Another means of feeding occurs where the food slips past the cell membrane and thereby enters the cell.� There is no vacuole formed in this type.� Digestive enzymes diffuse into the vacuole and dissolve the food.� Indigestible portions are left in the vacuole.� Protein and carbohydrate enzymes are present in abundance, but there are few fat enzymes.� Egestion is accomplished by the vacuole migrating to the edge of the amoeba and eventually becoming located on the outside of the organism. ��������� Amoeboid Movement .--The plasmagel and plasmasol are interchangeable, the former holding the latter under some pressure.� When the plasmagel weakens or converts to plasmasol anywhere on the animal, the pressure forces the plasmasol out into a pseudopodium.� The plasmasol sets into a gel all along the edges of the pseudopodium in the form of a tube.� The posterior end of the cell then crumples up while converting plasmagel to plasmasol so as to form the new extension. ��������� Circulation is accomplished by movements of the animal itself, and respiration and excretion are simple diffusions through the cell membrane.� The Contractile Vacuole is usually located at the posterior end of the amoeba.� This is a water regulating mechanism that pumps out water that moves into the cell by osmosis.� There is an incidental expulsion of water products.� With an increase in the salt concentration of the medium the contractile vacuole slows down and finally stops.� A reduction of salt concentration results in a reactivation of the vacuole. ��������� Support & Protection .-- There is little support needed in a suspended animal like Amoeba, and there are no protective mechanisms. �However, when unfavorable environmental conditions occur Amoeba forms a cyst that can resist drying, temperature extremes, etc. ��������� Sensitivity & Conduction .-- Amoeba behaves as if it had a nervous system, which it does not.� A stimulus applied at one point on the animal body may cause any other portion to react.� The animal perceives and responds to environmental changes.� There is a positive response to food and weak light, and a negative response to all other stimuli.� It generally responds in some way to light, temperature, touch and chemical reactions.� There are no visible sensory or motor apparatus in the cytoplasm, but Amoeba is regarded as being generally sensitive. ��������� Reproduction is entirely asexual being effected by binary fission (cell division).� Size determines when A. proteus will reproduce, which is usually 150 microns.� Sexual processes doe occur within the class but not in this genus.� ��������� In the Phylum Sarcomastigophora Class Mastigophora (Flagellata) movement is primarily by means of a flagellum.� Amoeboid stages may occur in some phase of the life cycle, however.� But adults always move by the flagellum.� When parasitic they do not form spores.� Nutrition is holozoic, saprophytic or parasitic.� The Subclass Phytomastigina include green flagellates while Zoomastigina are the colorless flagellates. ��������� These animals occur primarily in fresh water and an abundance of them may produce a green scum.� Their size varies from 25-500 microns and the body wall is more rigid than that of the amoebae.� There is a rigid, grooved wall or pellicle present, however the ecto- and endoplasm are not well defined.� Nutrition is holophytic where the animal manufactures it own food by photosynthesis.� But in darkness it will live on dissolved nutrient material and thus is saprophytic.� Food is stored in paramylum bodies, and pyrenoid bodies occur in the center of the chloroplasts, which serve to regulate them.� In darkness chlorophyll disappears from the cell.� Circulation, excretion and respiration are the same as in Amoeba proteus. ��������� Contractile vacuoles are located around the reservoir whose function is to serves as exit to the vacuoles.� Locomotion is by movements of the flagellum.� The flagellum has a central core and is spirally wound with cytoplasm. �The flagellum separates into two extension in the reservoir and terminates in basal bodies. ��������� As for sensitivity, there is an eyespot, which is positive to weak or moderate light but negative to strong light or arkness.� Conduction is like Amoeba.� The basal bodies serve as a coordinating mechanism because their removal discoordinates the flagellum.� Reproduction is asexual with longitudinal binary fission.� All parts are regenerative and there is no sexual reproduction in Euglena although others of the class do show it.� Cyst formation occurs to withstand adverse environmental conditions. ������� ��Some species in the Phytomastigina order Dinoflagellata have an armor plate ( cellulose armor ) that is occasionally shed and replaced.� The order is a large group of importance in marine habitats as plankton.� Dinoflagellates produce the " Red Tide " in oceans that results in widespread fish kills. ��������� The flagella have been termed " Frog Flagella " that are diagrammed as follows: ���� �����In the Subclass Zoomastigina nutrition is holozoic, saprophytic and parasitic.� The animals are colorless.� The flagella are very numerous and their arrangement is anterior with one flagellum extended anteriorly and the other trailing.� They may be fastened to the side of the organism by an undulating membrane. ��������� Several genera of the Zoomastigina are of great importance to humans and animals because of their parasitic habits.� Trypanosoma causes " African Sleeping Sickness ", Trichomonas is a parasite of humans and animals, Leishmania causes a skin disease known as " Oriental Sore ," and Giardia is a severe human intestinal parasite.� Also of importance is that species may also produce oils instead of paramylum, which results in foul-smelling and foul-tasting water.���� On the other hand, termites possess a Zoomastigina symbiont that is of mutual benefit. ��������� Phytomastigina have a well-developed and pronounced colonial arrangement, which is true also of the Zoomastigina but not as pronounced.� The Phytomastigina genus Pandorina has 16-32 cells while Volvox has hundreds of cells in a gelatinous matrix.� Any division of labor limits the boundary between colonial organisms and multicellular organisms.� Volvox may be sometimes regarded as multicellular, but reproductive cells in Volvox function only to reproduce the organism.� Species in the order Protomonadina possess a funnel-shaped collar similar to cells that are found in the Porifera. ��������� Sexual reproduction in the Phytomastigina is especially prevalent. �Isogametes of identical appearance and behavior are formed or heterogametes may be the case as in Volvox. ��������� All members of the Phylum:� Apicomplexa (Sporozoa) are parasitic, and all produce spores at some stage.� There are no locomotory organelles in the mature stage, although the immature forms may possess them.� Life cycles vary from simple to complex. ��������� The incitant of malaria, Plasmodium vivax, has one of the most complicated life cycles.� There are alternates of sexual with asexual reproduction.� Malaria is considered to be one of the most important diseases of humans and it also affects animals extensively.� Its life cycle is as follows: Please see following plates for Example Structures of the Protista: Plate 1 = Different body shapes in Rotifera.

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Treatise on Zoology - Anatomy, Taxonomy, Biology. the

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It was once suggested that ciliary tracts on individual cells were coordinated by a primitive sort of cellular “nervous system,” but this hypothesis was never con- firmed. The epistome and protocoel (present only in the phylactolaemates) play no part in this process. Guide to the Identification of Marine Estuarine Invertebrates. A guide to common butterflies of Singapore. Other genera in- clude Branchiura, Clitellio, Limnodrilus, and Tubifex. The nauplius eye and frontal organs of the non- Malacostraca.

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Woodlice (Synopses of the British Fauna)

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Blood leaving the ventricle passes into a forked aorta, where the blood has an equal opportunity to travel through a circuit of vessels leading to the lungs or a circuit leading to the other organs. The Denver Museum of Nature & Science Mammal Collection contains approximately 15,500 specimens from around the world (1850 - present), with a focus on the Rocky Mountain and Great Plains regions. The number of neph- ridia varies: one pair in Bonellia; two pairs in Echiurus; three pairs in Urechis; and hundreds of pairs in Ikeda.

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Invertebrates: Classification, Evolution and Biodiversity

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Gnathostomulids are found worldwide, intersti- tially in marine sands, often occurring in high densities in anoxic, sulfide-rich conditions, from the intertidal BLASTOCOELOMATES AND OTHER PHYLA 375 Figure 12.33 Development in entoprocts. (A) A mater- nal Loxosomella bearing a bud and releasing larvae. (B) A larva of Loxosoma harmeri. (C) Metamorphosis of L. har- meri; the larval body forms the first zooid. (D) Metamor- phosis of Loxosoma leptoclini; the larva attaches and pro- duces a bud that becomes the first zooid. (A) UNCORRECTED PAGE PROOFS zone to depths of hundreds of meters.

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Guide to the Freshwater Annelida (Polychaeta, Naidid and

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Rice (eds.), Microscopic Anatomy of Invertebrates Vol. 12: Onychophora, Chilopoda, and Lesser Protostomata, Wiley-Liss, New York, pp. 185–236. Instead of injecting a vermigon, the female cyprid has long, slender antennules that it uses to attach to the abdomen of the host, one of which actually penetrates the host’s cuticle, becomes hollow, and serves for the passage of embryonic cells from cyprid larva to host. Many leeches feed on other invertebrates, but some blood-sucking parasites feed by attaching temporarily to other animals, including humans.

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The Mollusks of the Arid Southwest

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The compound eyes of xiphosurans are very different from those of other Arthropoda, suggesting they might have evolved apart from the tetrapartite condition seen in Crustacea and Hexapoda (or that they are somehow derived from the crustacean tetra- partite condition). PHYLUM CNIDARIA CLASS HYDROZOA: Hydroids and hydromedusae* (Figure 8.1A–D). For ectoprocts these are: (3) colonial lifestyles, (4) retract- able lophophore, (5) loss of nephridia, and (6) production of brown bodies.

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Minibeast Homes (Acorn: Comparing Minibeasts)

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They differed from nautiloids in having shell septa that were highly fluted on the periphery, forming complex mazelike septal sutures. These animals have pointed teeth for grabbing and tearing their food. Fifty thousand species might seem like a lot. External skeletons developed in the ocean and allowed animals the opportunity to invade the land where the plants that had already evolved to survive on land could provide many open niches and food sources.

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Protozoan Plankton Ecology

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Action of Caenorhabditis elegans GATA factor END-1 in Xenopus suggests that similar mechanisms initiate endoderm development in Ecdysozoa and vertebrates. The importance of this concept is being increasingly rec- ognized and applied to biological systems. The hind part of the opisthosoma bears the anus and the spinnerets (the latter are situated near the middle of the opisthosoma in the Mesothelae). Thus, we see clearly the evi- dence of the chordate nature of these animals retained through paedomorphosis—evidence that is present only during developmental stages of other urochor- dates. (The phenomenon of paedomorphosis is dis- cussed in Chapter 4.) The pharynx of appendicularians is reduced and bears only two clefts.

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Invertebrate Historecognition (Bodega Marine Laboratory

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However, secondary LOPHOPHORATES 5 Figure 21.2 Phoronid internal anatomy. (A) The trunk of a phoronid (cross section). Ovovivipar- PHYLUM ARTHROPODA: THE CHELICERIFORMES 37 Ground Figure 19.26 Mating and viviparity in scorpions. (A) A pair of scorpions in courtship position; the two mates engage in a “push-pull” mating “dance” whereby the male positions the female over his spermatophore (B), which he has attached to the ground. (C) An ovarian diverticulum with enclosed embryo from the scorpion Hormurus. (A) (B) (C) UNCORRECTED PAGE PROOFS 38 CHAPTER NINETEENUNCORRECTED PAGE PROOFS (A) (B) (C) (D) (E) (F) (G) (H) (I) (J) (K) fpo copydot ordered fpo copydot ordered fpo slide here ous scorpions, on the other hand, produce yolky eggs that cleave meroblastically.

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