Biodiversity unit 3

Plants Architecture - Plant needs i. collection & conversion of solar energy -> leaves ii. positioning & support of leaves -> stems iii. anchorage & absorption -> roots iv. transport -> vascular system Leaf Structure - Epidermis, Mesophyll, and Vein (Vascular Bundle) Epidermis contains what? - - Cuticle - Guard cells with Stomata Epidermis - outermost cell layer of a plant body cutin: (wax) excreted by epidermis Cuticle - Waxy waterproof covering of a plant. Produced by the epidermis and has wax to resist desiccation. Guard Cells - Responsible for opening and closing stomata. Works together with stomata to regulate gas exchange. Prevents movement of water ACROSS surface Stomata - Small openings on the underside of a leaf through which oxygen and carbon dioxide can move. Mostly on lower surfaces, sometimes on upper surfaces. Found on both surfaces. Allows for gas exchange. 2 aspects of Photosynthesis - light dependent reactions light independent reactions Mesophyll contains what? - - Parenchyma - Dicots have Palisade & Spongy Layers Mesophyll - Middle leaf structures photosynthetic layer. Parenchyma - Ground tissue that forms the bulk of the mesophyll Can be modified into collenchyma and sclerenchyma Thin and flexible cells Most common and versatile ground tissue Used for metabolic functions and storage of organic products Palisade & Spongy layers - Palisade layer: where light dependent reactions occur, near the surface. Top part of the mesophyll in dicot plants. Spongy mesophyll or spongy parenchyma: soft lower layer. Has access to CO2 through stomata. Kelvin Cycle: where carbon fixation occurs, converting nonorganic CO2 into sugars. Vein (Vascular bundle) - Transports materials throughout the leaf and contains the xylem and phloem. Separating the VB = damage. Stem Structure - Epidermis, Cortex, Collenchyma, Sclerenchyma, Vascular Tissues Xylem - (Xylem Up) Distributes water from roots throughout Aimed towards stem Red Tells age of tree Contains: tracheids & vessel members Tracheids - Thin, hollow, narrow tube, dead cells with perforated, tapered ends. Vestigial structure First kind of tube made Present in early vascular plants and present in angiosperms and gymnosperms (slow flow) Vessel Members - Thick, hollow, wide tube, dead cells with large holes on end. Clearly visible Phloem - (Phloem Down) Distributes the products of photosynthesis (sugary water) to plants tissues. Blue Contains: Sieve tube members (element) & Companion cells Sieve Tube Members - hollow, living cells with perforated cells Companion Cells - living cells that help keep sieve tube member cells alive. Production of sugars in Kelvin Cycle require transportation done by companion cells into phloem Which 4 cell types is most active metabolically when fully functional? - companion cells Epidermis in Trees - is replaced by bark or cork. Produced by the cork cambium (tissues that produce other tissues). Cork (dead) = phloem (alive) Cork cambium produces cork. Trees grow wider cause xylem will get clogged The cork is produced when? - Secondary phloem Composition of Bark - is produced from phloem, cork cambium, or cork. Lenticels - cracks in the bark to facilitate gas exchange Secondary Growth - How a plant increases in girth (diameter) 1. Vascular Cambium 2. Cork Cambium 3. Wood 4. Bark 5. Lenticels 6. "Girdling Plants" Wood - produced by xylem. annual rings Heartwood: clogged xylem, little water transport. Located deeper into trunk, harder wood Sapwood: newer xylem, free flowing water transport. Phloem makes sap. Girdling Plants - Weed-Whakers Cutting a HORIZONTAL band around the circumference of the plant, can be deadly because the vascular cambium, in which nutrients and water travel vertically, can be damaged. What happens to initial phloem? - it gets crushed What happens to the xylem? - it gets clogged Cortex - Yellow layer inside epidermis Separated by a ring of vascular bundles. Ground Tissue System - Includes various cells specialized for functions such as storage, photosynthesis, and support Types of Ground Tissue - Parenchyma, Collenchyma, Sclerenchyma Collenchyma - celery fibers for support Sclerenchyma - hard fibers & nodules responsible for support (ex) rope Sclerids - nodules glued together to form shells of nuts. Fibers - secretions that reinforce the stem Pith - Middle of stem, large because it contains nutrients. Separated by a ring of vascular bundles. Replaced by xylem Procambium - Becomes Vascular Cambium Makes xylem inward and phloem outward Grows in rings Gives rise to vascular tissues Forms advanced tissues Monocots - have no cortex Germ layers - = stem cells Root Structure - i. Epidermis (permeable) with root hairs ii. Cortex iii. Endodermis with Casparian strips iv. Stele v. Apoplastic vs Symplastic pathways Stele - Central cylinder with vascular tissues inside. Caspian strips - wax, prevents water from growing in between cells Used to aid a plant and tell weather in the past - Annual rings Apoplastic vs. Symplastic pathway - Water enters through root epidermis and passes in the spaces "between" cortex cells apoplastically until reaching the endodermis. Casparian strips prevent water from passing between endodermal cells. Thus, water is forced through the cell membranes symplastically where it is filtered before reaching the vascular tissues within the stele = osmosis Root nodules & Symbiotic bacteria - Bacteria fix nitrogen and are housed in root nodules to supply "fertilizer," thus allowing the plant to thrive, even in soils that are nutrient poor. Nitrogenace- enzyme that breaks down the triple bond in nitrogen Microbes contain this enzyme and they're anaerobic. Mycorrhizae: most plants have an association between their roots and fungi in the soil. This association is critical in aiding water/mineral uptake by the plant. Abiotic Fixation - Doesn't involve organisms Lightning converts nitrogen into other sources because N2 isn't a usable form Less important because lightning doesn't occur enough to be useful for plants Biotic Fixation - Process by which free nitrogen (N2) is extracted from the atmosphere and converted (fixed) into nitrogen compounds which are plant nutrients (fertilizer). In nature, this process is carried out by certain bacteria such as cyanobacteria Usable forms of nitrogen for plants - Nitrate NO3 Nitrite NO2 Ammonia NH3 Vegetative Asexual Reproductive modes of flowering plants - Runner (stolon), strawberry Rhizome- underground stem (bermuda grass) Corm- modified stem Tuber- modified underground stem. Gives rise to new growth onion; Potato (however some potatoes are roots) Bulb- modified stem Parthenogenesis - development of egg without fertilization Propagation - vegetative reproductive. Cut off a piece of plant off and it grows. Plant Development - '... After germination" Upward growth -Epicotyl or Coleoptile -Phototropism Downward growth Radicle or Hypocotyl Gravitropism Positively Phototropic - Growth in response to light Structures responsible for downward growth - Radicle and Hypocotyl Contain statoliths (little rocks) that can sense movement in bottom of cell, triggering the plant to grow towards the center of the earth (down) Positive Gravitropism - grows in the direction of gravity via statolith sensors Meristematic Tissues - Plants version of germ cells Apical Meristems - responsible for increase in plant HEIGHT Lateral Meristem - responsible for increase in plant DIAMETER (girth) Meristems vs. Germ Cells - A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing. A germ cell is any biological cell that gives rise to the gametes of an organism that reproduces sexually. Meristems are in plants and germ cells are in humans but in essence are essentially preforming the same function Three Primary Meristems - 1. Protoderm = Epidermis 2. Ground Meristem = Parenchyma, Collenchyma, Sclerenchyma = undifferentiated or modified to store pith 3. Procambium = VB w/ xylem and phloem Exchange & Transport - i. Plants obtain gases, nutrients, minerals, & water via internal fluids ii. Gas exchange begins with the stomata; roots, lenticils iii. Internal transport = xylem & phloem Fluid movement in xylem - Adhesion: Attraction of 2 of different things; water molecules bind to cell wall This makes sure that the water doesn't go back down (capillary action) Cohesion: Attraction of two of the same things sticking together; water molecules bind to one another via hydrogen bonding which pulls water molecules upward through xylem, like beads on a string Evaporation: as water evaporates, it pulls on other water molecules that haven't been evaporated yet Osmosis: Occurs in roots (root pressure) Low solute concentration to high solute concentration Capillary Action: allows water to go up, just a little bit Transpiration Pull aka Cohesion/Adhesion Tension - The main motive force for transporting water up to the top of a plant (sometimes several hundred feet) As water evaporates from the leaf's surface the cohesive-adhesive properties of water pull water molecules from below establishing a water tension and pressure Drawbacks w/ Transpiration Pull - It requires significant water loss from the plant. In dry conditions or arid environments, this water loss for vertical transport can be critical in plants Therefore, a replenishing water supply is vital for the roots Water loss in the tropics doesn't matter cause its always raining there. Water evaporation = shade Fluid movement in Phloem - Mass Flow: An active transport mechanism Source vs. Sink: Source: Sugars produced by the leaves Sink: Sugars produced by the rest of the plant. Gravity can assist in this downward movement, however getting the sugars into the cells of the Phloem requires energy Kingdom Animalia - 1. Multicellular 2. Heterotrophs 3. Lack Cell Walls Two Major Groups of Kingdom Animalia - 1. Invertebrates (no backbone) about 15-30 million 2. Vertebrates (chordates with backbones and spinal columns) about 50,000. 30,000 of the 50,000 are fishes There are animal species that haven't been described yet. 3 million have been described. Phylum Cortada - vertebrates, fish, amphibians, mammals, birds, reptiles Metazoa - transition from an animal-like protists to multicellular (choanoflagellate) Advantages: 1. Large Size 2. Increased Mobility 3. Stable Internal Environment (Homeostasis) 4. Relative independence from environment Radial Symmetry - Diploblastic Can be cut in half anywhere along a central axis No head Little movement Bilateral Symmetry - Triploblastic Can be divided down a central line but cannot be cut anywhere Cephalization: concentration of sensory structures in the head (ex) orchids, humans Asymmetry - No symmetry Sponges Ontogeny - = development "Ontogeny recapitulates phylogeny" Significant similarities among true appearance of vertebrate embryos due to evolution. Most abundant skeleton - exoskeleton which tells the shape of the animal Problem: gets in the way of growth Largest animal that ever existed on this plant - blue whale weight (mass) that makes them big Largest organism on the planet - Humungous fungus Largest land animal - elephant Largest invertebrate - squid First organism to conquer land - Reptiles, by producing a self-enclosed egg (aka shell egg). (ex) birds # 1 species diversity - tropical rain forests # 2 species diversity macroscopically - coral reefs #1 species abundance and diversity - arthropods #2 species abundance and diversity - mollusks # 3 species abundancy - Roundworms 1st organism to be cephalized and have excretory system - flatworms 1st organism to have a closed circulatory system and complete digestive tract - ribbon worms Secondary Compounds - how plants defend themselves from insects, creating medicine. Almost all animals are - arthropods -> insects -> beetles Most abundant and diverse Embryology - i. Cleavage patterns: early cell divisions ii. Cell fate Radial Cleavage - new cells placed directly beside or on top of previous cells; deuterosome feature Spiral Cleavage - new cells placed at juncture between previous cells; protostome feature Determinate Cell Fate - fate of cells determined early; separated early cells incapable of developing into entire organism; protostome feature determined @ 4 cell stage Indeterminate Cell Fate - fate of cells determined relatively late; separated early cells can develop into entire organism; allows for 'twinning' or genetically identical individuals; deuterosome feature (ex) humans Developmental Stages - 1. Morula 2. Blastula 3. Gastrulation 4. Gastrula 5. Germ Layers Morula - Solid ball of cells First stage of development in animals Blastula - Hollow ball of cells Blastocoel is in the center Second stage of development in animals Blastocoel - Chamber (body cavity) of hollow area within a blastula Blastocoel is replaced by - mesoderm and coelm Gastrulation - Pushing in of cells into the blastocoel Third stage of development in animals Byproduct of gastrulation - blastopore Gastrula - Develops from gastrulation that creates the cell layers Early multicellular embryo, composed of two or more germinal layers of cells from which the various organs later derive Fourth stage of development in animals Blastopore - An opening which connects a portion of the body cavity to the outside environment Can become either the mouth or anus Archenteron (Gut) - aka Primitive GI Track most animals have 2 Schizocoely - derived from split in mesoderm; protostome feature Enterocoely - derived from outgrowth of archenteron; deuterostome feature Coelom - body cavity lined entirely by mesoderm Pseudocoelom - body cavity lined partially by mesoderm Acooelomate - no cavity between body wall and organs "False Coelom" Protostome - If the blastopore becomes a mouth first Formed from Schizocoely development Deuterostome - If the blastopore become anus first Humans are deuterostomes Formed from Enterocoely development Extinct vs Extant - Extinct :no longer here (ex) Sea fern Extant: exists today Fossils found on sediments of mountains due to plate tectonics even though they lived in water, during Cambian period Parazoans - "Poorly defined tissues" Phylum Placozoa - the most primitive metazoan (ex) sponges Phylum Porifera - Sponges (can be monoecious or dioecious) Sessile- don't move around Filter water through canal system lined by flagellated collar or choanocyte cells Mostly marine Regenerative characteristics Body filled with spores Poorly defined tissues- Parazoan Three body plans: - Asconoid: sac like, simple Syconoid: folded Leuconoid: most complex design Outer body layers: - Porocytes:tubular cells which make up the pores of a sponge Myocytes: moving and contracting water, functions like muscle Middle layers (mesophyll) - Spicules: hard skeletal elements (provide support). Either composed of silicon dioxide or calcium carbonate Spongin: produces spongy composition, soft, makes up body wall Amoebocytes: give rise to all cells in sponges. Can transform themselves into any other cell in the sponge. All cells can revert back to amoebocytes. Collencytes: neuron-like cells Inner layer - Choanocytes: or collar cells, creates current that draws water in for filtration Asexual Reproduction - Regeneration Budding (like propagation) Gemmules: packed highly spicule cover of amoebocytes. During unfavorable conditions (rain), activates gemmule to soften up to prevent desiccation and release stem cells. After gemmules have been released, sponge dies. Sexual Reproduction - Dioecious: mostly all animals Monoecious: aka hermaphrodite. Almost all animals reproduce in the water. Class Calcarea - Spicules made of calcium carbonate. Class Hexactinellida - "Glass sponges" Contain 6 rayed spicules made of silica (glass) Class Demospongiae - Most common and abundant sponge Leuconoid Class Sclerospongiae - limited species Branch Eumetazoa - First "true" tissues Grade Radiata Phylum Cnidaria - Mouth w/ tentacles No anus, but has gut Cnidae Diploblastic w/ organs: two true tissues; however, cnidarians have 3 body layers (ecto, endo, meso- NOT TISSUES) Incomplete digestive tract "Nerve net": nervous system not concentrated in the head, but rather spread out Two Body Plans - Medusa: jellyfish shape. Can move to disperse gametes (either monoecious or dioecious). Diploid. Polyp: sea flower shape. Diploid Metagenesis - Life cycle of jellyfish NOT complex, NOT Alternation of Generations going from polyp to medusa form & vice versa Cnidae - Nematocysts: stinging structures. Protein toxin found in man o wars. Spriocysts: adhesive, only found on anthozoa Ptychocysts: tube construction found in one kind of sea anemone called tube sea anemone Classification of Cnidaria - Class Hydrozoa Class Scyphozoa Class Anthozoa All classes have nematocysts, except Anthozoa has all 3 cnidae. Class Hydrozoa - Medusoid or Polypoid -"Hydromedusae" small Polymorphism: multiple forms of hydroids -Gastrozooid -Gonozooid (gonangium) -Dactylozooid -Skeletozooid Acellular mesoglea Cnidae in epidermis (nematocyst) Hydra: Freshwater (atypical) Obelia "a hydroid" "Hermit crab" hydroid Dactylozooid lashing - Contains toxins (nematocysts) shaped like spiral. Only found on hermit crab shells occupied by the crab.When hermit crabs leave shell, dactylozooids disappear. Dactyl. communicates with crab through cephalization by stinging it to do things. Octopus is predator. Physalia - "Portuguese-man-of-war" "a floating, polymorphic colony" Modified medusa. Move with currents/wind. Man o war fish hang around in the tentacles Fire corals - not true coral. Can produce calcium carbonate. Take on different shapes. Cause injuries upon touch. Class Scyphozoa - Medusoid or Polypoid -"Scyphomedusae" large Cellular mesoglea: less organized cells, not close to tissues Cnidae in epidermis & gastrodermis Life cycle -Scyphistoma: young polyp -Strobilation: asexual reproduction -Ephyra: young, unique medusa -Planula: Unique larvae found within cnidarians. Swim around to find body and form polyp called scyphistoma, then engages in asex reproduction called strobilation to form young medusa called ephyrae which disperses gametes in gonad. Common "Jellyfish" Cubomedusa: deadliest animal on planet "Sea wasp" "Box jelly fish": not lethal Class Anthozoa - Polyploid only Cellular mesoglea Cnidae in epidermis & gastrodermis Septa (mesenteries) in gut Reproduction -Sexual (Body is diecious or mono) -Asexual (Budding, fission - Longitudinal/transverse) Sea lice - larvae stage of jellyfish (planula) Anthozoan Diversity - Sea anemones: protect hermit crabs; however when no predators present, hermit crabs eat sea anemone Corals: colony of sea anemone -Hermatypic Corals: gives coral its color. Tissues are transparent. - Dinoflagellates w/ Zooxanthellae: assist in removing calcium carbonate. Sensitive to rise in temperatures; can be ejected from coral causing bleaching due to global warming and carbon emissions. -Scleractinians (hard coral) or Hexacorallia (6 tenticles for each polyp) -Coral bleaching Ahermatypic Corals: do not form calcium carbonate houses -Octocorals or Gorgonians: 8 tenticles for each polyp -Sea pen -Sea fan -Sea whip Coral Reefs: colorful fish Counterstaining - top part of fish dark , bottom part light. Giving most fish a silver color. Not found in coral reefs. Most fishes are - laterally compressed Phylum Ctenophora - Medusa-like, w/o nematocysts (However, unless ingested) 8 comb rows, with 2 tentacles (usually) Colloblasts: radial symmetry, adhesion Two classes: Tentaculata (have tenticles) & Nuda (no tenticles) Comb Jellyfish: Highly predatory Phylum Platyhelminthes - i. General characteristics -Dorso-ventrally flattened -Cephalized (1st to be cephalized) Radial -> Bilateral -Triploblastic & Acoelomate -Incomplete digestive system -Protonephridia (Flame cells): excretory system. Flicking of cilia makes them flame cells. (ex) flatworms Sexual Reproduction - (mostly hermaphroditic) Hypodermic impregnation: penis fencing. Asexual Reproduction - -Fission -Regeneration Movement - Live under rocks in streams or rivers -Adhesive glands: adheres to rock like super glue -Releaser glands: solvent that releases them from rock -Taxis: movement response using head and eyes Light: negatively phototaxis- strays away from light Current: positively current taxis - moves towards current to bring back home Helminthologist - someone who studies worms Classification of Platyhelminthes - Class Turbellaria Class Trematoda Class Cestoda Class Turbellaria - Free-living, small, mostly marine. Rhabdites aka nematocyte, very colorful Class Trematoda - Parasitic "Flukes" Syncytium: body covering that protects them from chemicals Suckers: for attachment Complex life cycles w/ alternating hosts -Primary Host: aka Definitive Host- where adult parasite is formed - Intermediate Host: aka vector: accidentally transferred parasite or disease "Chinese Liver Fluke": under cooked meat Class Cestoda - Parasitic "Tapeworms" Lack digestive tracts. Scolex (for attachment) & Proglottids (repeating body segments). Pork/Beef Tapeworms from poorly cooked meats Adaptations/Characteristics for Parasitism - Adhesive organ Sense organs reduced Digestive tract reduced/lost: (fed off host) Body wall protection: against chemicals in stomach that break them down Fecundity increased: reproductive output of different species, the ability to produce many different offspring Larval stages to facilitate passage from host to another Phylum Nemertea - "Ribbon" worms (flat) General characteristics -Proboscis (tenticles for feeding and defense) -Cephalized -Complete digestive tract (1st animal to have this) -Closed circulatory system (1st animal to have this) Feeding structures -Proboscis w/ stylet -Rhynchodeum: opening to the outside -Rhynchocoel: not true body cavity, opened body cavity Reproduction -Sexual -Asexual: fragmentation- chop it up, it can make a new self with no confusion on the placement of head & tail Pseudocoelomata - "Aschelminthes"- sac worms, organs free floating Wormlike, parasites. Eutely: same # of cells in every individual, critical for development Parthenogenesis Phylum Rotifera and Nematoda - "Roundworms" & Rotifers Abundant in soil, free-living & parasitic forms Unsegmented Longitudinal muscles & longitudinal whipping Cloaca: opening for the exit of two or more systems, one of them being digestive. Used for consolidation. Differentiates them from annelids, primitive structure Nematode Parasitism - "Affecting most group" Roundworms Eye worms Dragon worms Elephantiasis Trickenela Heart Worm Eucoelomata - "Protostomia & Deuterostomia" -Lophophorate animals: possess both protostome and deuterostome characteristics -Coelom formation varies -Blastopore fate varies -Ribosomes protostome-like i.Phylum Bryozoa (Ectoprocta) ii.Phylum Brachiopoda iii.Phylum Phoronida Protostomes - Phylum Mollusca Phylum Annelida Phylum Mollusca - General Characteristics -Abundant, aquatic & terrestrial forms. Body plan: -Soft parts: Mantle (produce shell) , Head/Foot, Visceral Mass (holds organs). -Hard parts: Shell. H.A.M. = Hypothetical Ancestral Mollusk -Coelom Excretory system: -Kidney=Metanephridia=Coelomoduct=Gonoduct. -Circulatory system: Open vs Closed -Shell: Periostracum, Primastic layer, Nacreous layer. -Reproduction: Trochophore larva, Veliger larva. Circulatory system: Open - Most mollusks have limited blood vessels. Thus, the blood interacts directly with the tissues - this defines the Hemocoel. Periostracum - Leathery, protein layer on the outside of "some" shells. Prismatic Layer - Perpendicular layer of calcium carbonate. Nacreous Layer - Horizontal layer of calcium carbonate Trochophore Larva - Characteristic larval form found in many Mollusks, and in many other protostomes such as annelids. Veliger Larva - In many Mollusks, the trochophore larva will transition into a? Larvae similar in annelids and mollusks suggests - that they have a common ancestor Mantle - Periostracum, Prismatic Layer, and Nacreous Layer are all produced by the? Classification of Mollusca - Class Monoplacophora Class Polyplacophora Class Gastropoda Class Bivalvia Class Scaphopoda Class Cephalopoda Class Monoplacophora - Neopilina -Multiple gills, muscles, nephridia & gonads. Primitive group with a single, conical-shaped shell. Neopilina - This species represents a group that links mollusks with the annelids. Has segmented gills, muscles, nephridia and gonads. Class Polyplacophora - "Chitons" Shell consists of 8 articulated plates. Poorly-developed head. -Articulated shell Class Gastropoda - -Shell types: Planospiral (spiriling in one plane) vs Helicospiral (most snails) Operculum (shield covering made of chiton) & Shell aperture (opening in the shell) -Shell-less forms: Nudibranch (undergo torsion and then detorsion) & (has no shell, just filled with nematocysts) -Torsion & visceral mass Planospiral - These shells are coiled to form in a single plane, so that the coils can be seen from the side, but if turned 90 degrees, the coils are not obvious. Helicospiral - These shells are coiled to form a cone shaped, spiraled shell. Most snails. Operculum - Chitinous lid or cover for when the snail pulls itself back in the shell, this cover fits in the shell opening or aperture perfectly. Nudibranch - These animals forgo the shell, but instead use the nematocysts from consumed cnidarians for their own defense. Torsion & Visceral Mass - Most snails will undergo a 180 degree twisting during embryonic development to bring their shell forward for easier balance and movement. Nudibranchs will also undergo torsion, but apparently because there is no shells will twist back to where they started. This return to the original position is called Detorsion. Class Bivalvia - -Shell: Umbo, Hinge ligament -Adductor muscles -Protractor vs Retractor -Mantle cavity -Siphon: Incurrent vs Excurrent -Digestive system -Bivalve diversity -Oysters & Pearl formation -Scallop: Eye spots -Giant clam -Shipworm -Freshwater -Glochidia larvae (mantle shaped like fish) Umbo - First, thus oldest, part of the shell. Hinge ligament - This ligament forces the shell to open under constant pressure. Adductor muscles - These muscles force the shell to close. For "real" scallops, this is what we eat. Oysters produce _____ when trying to cover foreign material within the shell. - Pearl Protractor muscles - These muscles push the foot forward. Blood fills up the tip of the foot. Retractor muscles - These muscles contract and pull the clam towards the expanded foot, thus enabling the animal to move forward. Mantle Cavity - This cavity is where water enters and exits via special modified mantle tissue called Incurrent and Excurrent siphons. Digestive system - Most of the visceral mass is composed of digestive organs. Eye spots - Scallops have distinct, multiple eyes on the edge of the mantle allowing them to see pretty well. Giant clam - These animals do not feed, but rather have zooxanthallae packed into the edge of the mantle tissue. Have symbionts which undergo photsynthesis. Shipworm - These wormlike clams, using chemical secretions, feed on wood. Class Scaphopoda - "Tusk Shells" -Burrowing Class Cephalopoda - "Squids & Octopods" -Shell absent, reduced or spiraled. -Tentacles/arms w/ suckers. -Siphon -"Intelligence" -Eyes well developed -Closed circulation -Beak (w/poison) -Ink Gland -Chromatophores -Other cephalopods -Cuttlefish -Chambered Nautilus -Siphuncle Squids - Largest of all invertebrates. 60-90 feet long One of the more intelligent of all animals. Siphon - Used to propel the animal quickly through the water column. Blue-ringed octopus (Poison in beak) - One of the dealiest animals on earth. Ink Gland - Cephalopods can inject a cloud of ink from what structure in their body? Chromatophores - Special pigment-containing structures in cells, which can allow for rapid changes in color/patterns in many cephalopods. Highly metabolic animals don't have an - open circulatory system Cuttlefish - Squid-like animal that has an internal shell commonly called the cuttlebone - although it is not actually bone. Chambered Nautilus - Squid-like animal that lives in a planospiral shell, which is partitioned internally into gas-filled chambers used for buoyancy. They are found in deep, dark, cold oceanic waters. Siphuncle - This tube of tissue that travels into each chamber of the Nautilus shell; responsible for producing gases used in maintaining neutral bouyancy. Phylum Annelida - -Vermiform -Metamerism -Homonomous w/ metameres=segments -Setae=Chaetae -Parapodia -Closed circulation -Metanephridia Contain both Protostome and Deuterostome characteristics - Transitional Species Shells Mesoglea - when the middle body layer (which is not a tissue) glues the outer and inner layers. So its a middle layer of glue. Larvae - is a juvenile that undergoes a metamorphosis (ex) butterfly, humans, magnet, caterpillar