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Marine Invertebrates Main Ideas Classification and Comparison of all invertebrates Sponges are asymmetric, sessile animals that filter food from the water circulating through their bodies. Sponges provide habitats for other animals. Main Ideas Cnidarians and ctenophores exhibit radial symmetry. Cnidarians posses a high specialized stinging cell used to capture prey and for protection. Main Ideas Marine Worms exhibit bilateral symmetry. Turbellarians are free living flatworms; flukes and tapeworms are parasitic. Nematodes are abundant and important members of the meio-fauna Main Ideas Several other worm-like animals like ribbon worms, spiny headed worms, peanut worms, acorn worms and beard worms play important ecological roles in the marine environment. What are animals? Multi-cellular Eukaryotic cells with no cell walls Cannot produce their own food All animals, with the exception of adult sponges can actively move. Classification of Animals Living creatures inhabit almost every part of our waters and land, and they exist in an astonishing variety of shapes and sizes. Over a million kinds of animals and plants are known, and probably millions more are yet to be discovered and described. Classification of Animals To study this vast number of life forms, biologists classify organisms into groups and subgroups that have similar anatomy (body parts) and physiology (the workings of those parts). Classification of Animals All animals are members of the animal kingdom. A kingdom is divided into smaller groups, the most inclusive being the phyla (the singular is phylum). A phylum is successively divided into classes, orders, families, genus, and species. Each group may be further divided into subgroups, such as subphyla or subclasses. Classification of Animals Kingdom- Phylum-Class-Order-FamilyGenus-Species When talking about an animal you are just naming the genus and species. Use Latin and Greek roots for unfamiliar names. Example: lobster is Homarus (genus) gammarus (species) Invertebrates: Spiny Lobster Classification System Using this classification system, we can study the characteristics of one kind of organism or compare the common characteristics of several groups. Classification System In the phylum Chordata is a subphylum Vertebrata, which includes all animals with backbones. Among its members are animals such as fish, frogs, lizards, birds, and humans. Animals are often divided into two groups, vertebrates and invertebrates. Although this division is convenient, it is confusing because invertebrates do not make up a formal scientific group. Classification System The term invertebrate does not refer to a strictly defined scientific group, it is a handy term meaning “any animal without a backbone.” All kinds of animals except vertebrates are invertebrates. Invertebrates are far more abundant in the ocean and on land than vertebrates are. Invertebrates: Tube Sponges and Coral Invertebrates: Long Spined Sea Urchin hiding in Coral Sponges or Porifera Come in an variety of colors and an amazing array of shapes. The shapes are determined by the bottom sediment, the material they are growing in and ocean currents. Red, yellow, green, orange and purple are extremely common. Green Sponge Sponges They are predominantly marine Exception family of Spongillidae who live in freshwater. Sponges are benthic creatures, found at all latitudes beneath the world's oceans, and from the intertidal to the deep-sea. Natural Dead Sponges- Lose their color when dead Sponges They are sessile- means doesn’t move much. It has been shown that some younger sponges are able to move slowly (up to 4 mm per day). Sponges Some sponges bore into the shells of bivalves (mussels and clams) gastropods, and the colonial skeletons of corals by slowly etching away chips of calcareous material. Sponge covering a shell of bivalve Sponges A sponge can settle on a snail shell that is being used by a hermit crab; an unusual association can be formed. This sponge/crab association results in a mobile sponge. Sponge and Crab Generalized Anatomy of a Sponge Body is built around a system of water canals. Body full of tiny pores called ostia in which water passes through. Water is source of nutrients and oxygen, and carries away wastes. Water is like the blood of the human body, circulating food and nutrients throughout the sponge. Generalized Anatomy of a Sponge Water comes in through ostia, and enters large cavity called spongocoel. Water exits out the osculum. See handout: Anatomy of a sponge. Sponge Size and Body Forms Asconoid sponge: the simplest form, tubular and small. Usually found in clusters. During evolution, sponges found it helped out if they could grow by folding over areas of the sponge. This increased the amount of volume of water it could filter (thus get nutrients) Asconoid Sponge- Magnified Sponge Size and Body Forms Syconoid Sponges: has body wall folding to it, but only a small amount. Leuconoid Sponges: many folds to these types of sponges. Largest type of sponges. Syconoid Sponges Leuconoid Sponges Nutrition and Digestion Suspension Feeders: feed on food suspended in water. Filter feeders: because they filter their food from the water. Collar cells trap the food that is flowing in with the water. Collar cells have flagella, which will push the water through the cells. Flowing water also takes out wastes produced by the sponge. Water: digestive system Collar Cells in Sponges Sponge Reproduction Depends on type of sponge. Sexually: egg and sperm released into the water and hope to god that they combine. Sponges are hermaphrodites, thus producing both sperm and egg cells. Asexually: budding Commercially sold sponges cut the buds off the sponge, thus leaving more in the stead of the adult one they killed. Asexual Reproduction: Budding Ecological Role of Sponges Compete for space with other bottom dwelling organisms. Need good material to attach to- if a fertilized baby sponge doesn’t get it, it dies. Produce chemicals to kill other species around them to make room. Ecological Role of Sponges Few animals eat sponges- eating the spicules is like eating needles. Chemicals to kill off other species from settling next to them, also kill deter grazing. Only Sea Turtles and a couple other animals are brave enough to eat them. Sea Turtle Poop is composed of 95% of spicules. Has a toughly lined digestive tract. Hawksbill Sea Turtle eats Sponges Sponges and Symbiotic Relationships Sponge houses bacteria, that provide food for sponge while the bacteria gains nutrients and a house. Cyanobacteria is a photosynthesizer, which produces its own food and shares with the sponge. Sponges and crabs: the sponge grows on the crab becoming motile. The crab gets camouflage. Sponge and Hermit Crab Introduction to Cnidarians: Stinging Celled Animals Sea Anemone Jellyfish Cnidarians Cnid: nettle Includes Corals, Sea Anemones and Jellyfish Corals: located near tropical islands Sea Anemones: Cold artic waters to the equator Hydra: microscopic cnidarians in freshwater Jellyfish: float near surface of ocean Can also exist in streams Brain Coral Elk Horn Coral Common Characteristics Jelly-like materials Carnivorous Capture small drifting animals w/ tentacles Some brightly colored Graceful movement w/ tides Giant Sea Anemone Sea Plume (Soft Coral) Body Structure Outer layer: ectoderm has cells that capture food and secrete mucus Jelly-like material between two layers: MESOLGLEA Surround central cavity: gastrovasular cavity which extend to tentacles 2 Forms Medusa: body shaped like an umbrella, w/ tentacles hanging. Not sessile Jellyfish Polyp: top has tentacles, with a hollow cylinder that opens and closes at the top. Sessile: so can only eat what ever comes in contact w/ mouth. Corals and Sea Anemones Polyp Body Medusa Body Body Symmetry Radial Symmetry: extend from a central axis. Radial structure allows them to sting and capture organisms in any direction. Most sessile organisms have radial symmetry. Radial Symmetry Food Capture Unique long stinging cells called: Cnidocytes Long harpoon like tubes called: Nematocyst When the Nematocyst senses food is fires venom outward to stun the prey. Barbs line the harpoon-tube to attach prey. Stings Jellyfish sting to paralyze and capture food. All others do also. Potency of venom varies Portuguese Man of War: painful sting for human Sea Wasp (Australian jelly fish) will kill you. Sea Wasp Stings Some marine organisms are immune Clownfish and Anemone mutualism Shell-less mollusk Glaucus is a predator of man-of-war, eating it, and using the Cnidocytes for its own defenses. Turtles eat jellyfish w/ no problems Venom Is a protein Some people are allergic thus having a worse reaction. Treat a sting by breaking down the protein Chemically: meat tenderizer Thermally: apply heat to denature proteins Hydrostatic Skeleton Unlike sponges, sea anemones and jellyfish have no skeletal structure to support their soft tissue. They fill their gastrovascular cavity with water and close mouth tight. This puts the water under pressure like a balloon. If the Cnidarian contracts its body hard it loses water. It takes several minutes to pump the water back in. Propulsion When a ring of muscles contract, a jet of water is forced out. The jelly fish relaxes and then the umbrella reforms. Alternating muscles contract creating pulsating movements. Jellyfish are such poor swimmers that they are classified as plankton because they can not swim against a current. Digestion Tentacles move the food into their mouths. Prey is swallowed into the gastrovascular cavity and digested. Ectoderm cells produce enzymes, which break down the food. Can consume anything from plankton to small reef fish. Indigestible material is expelled through the mouth. Respiration and Nutrient Absorption Have neither respiratory or circulatory systems. Get Oxygen directly from water. Nutrients pas through the liquid between the cells, wastes pass out by the same route. Nervous System/Muscular System Consists of cells with long, thin fibers that respond to stimuli. Nerves send impulses to muscle cells. In the sea anemone muscular system consists of muscle cells lying in bands up and down the body wall and in a circle around the mouth. Body shortens when contractions occur. Nervous System/Muscular System (cont.) If one side contracts the anemone moves that direction. Mechanoreception- the ability to respond to a stimulus of touch or pressure. When something touches it…it moves Chemoreception – the ability to respond to chemical stimuli Crucial to finding foods, detecting harmful substances, and in some organisms selecting, attracting mates. Nervous System/Muscular System (cont.) Photoreception- ability to respond to changes in light intensity. Positive response – organism moves towards the stimulus. Negative response- organism moves away from the stimulus Reproduction Reproduce both sexually and asexually Sexual reproduction begins with the production of eggs and sperm Eggs in ovaries, sperm in testes. Fertilization occurs when the egg and sperm unite. Some species fertilization happens in the water, in others fertilization happens in the female. Reproduction (cont) New organism grows into a larva Larva swim by the use of cilia- small hair like structures. Because they can not swim against currents they are classified a plankton. Can drift for hundred of miles Attaches to a hard surface and grows into an adult Asexual Reproduction Asexual Reproduction Reproduction without eggs and sperm. Budding- like growing a new branch on a tree Cells on the side or base of the parent begin to bulge out. If many attached buds are produced , they form a large colony. In some organisms the bud detaches and settle down nearby. Regeneration Replace lost or damaged parts. Small damaged chunks may even regenerate into new organisms. Worms Display a great range in size, efficiency, complexity, and body structure. Long thin creatures that get around efficiently without legs. Different phyla = different degrees of complexity Flatworms – simple – barely more complex than a cnidarian Some may rival more advance organisms such as mollusks, snails, and oysters. Spaghetti Worms Fan Worms (gills visible) Worms Degree of complexity depends on different body features and systems. Have a Bilateral symmetry Like fish they have a definite front and rear. Organs for sensing light, touch and smell are in their heads Can detect the different environments they encounter. Organization Front of the worm is called the anterior end. Rear is called the posterior end. Under part is called ventral surface Upper part is called the dorsal surface. Six features and systems a) mesoderm, an intermediate body layer that forms muscle tissue b) central nervous system guided by a “brain” c) excretory system to eliminate some kinds of waste products d) complete digestive system, from an anterior mouth to a posterior anus e) coelom, a body cavity between the digestive tube and the external body wall f) circulatory system consisting of a series of tubes (vessels) filled with fluid (blood) to transport dissolved nutrients, oxygen, and waste products around the body rapidly and efficiently Flatworm Simple Worms: The Flatworms Least Complicated Live on land, in fresh water, in the ocean, and in or on other animals Symbiotic parasites (ex. Tapeworms) Can make humans or animals sick or kill them Marine flatworms are just a few centimeters long. Flatworms Some live symbiotically with crabs, clams, oysters, shrimp, and barnacles. Some brightly colored, other are drab and blend in. A three-layered body with no Coelom More complex then cndarians Flatworms have 3 layers ectoderm, endoderm, and mesoderm. Mesoderm is between the two other layers Cells specialize into a muscular system that enables the animal to move around. Flatworms Have a digestive system with only a single opening Cavity branches into all parts of the body. This feature is the source of the name for some marine flatworms (polycladida) These feed through a long, tubular pharynx Cells lining digestive cavity finish digesting food. Flatworms Undigested food come out the mouth as in Cndarians Have a CNS Mass of brain cells called a brain Sensory cells in the head detect changes in the environment. Sensory cells that detect light are clustered into two eyes in the head Sensory cells that detect water currents , solid objects, and chemicals are in two flap like projections on the head called auricles Living without a Circulatory System Flatworms have no circulatory system Get nutrients by diffusion. Body shape and constant contact with water facilitates absorption All their cells are wither close to their outer surface of digestive cavity. Flatworms: Excretory system Network runs the length of the animal and opens to the outside through small pores in the posterior region of the body. Have flagella that force the food down and out. Because this movement looks like a flickering fire, the structure is called a flame bulb. Fireworm Complex Worms: The Annelids Typically have segemented bodies Divided into repeating sections called segments with many internal orgains Earthworms are familiar members of this phylum Some annelid worms (earthworms) are important as fishing bait. Complex Worms: The Annelids Most marine annelid worms are poly-chaetes (Poly=many; chaeta=bristle) Polychaete worms are so named because most of their segments have muscular flaps called parapodia (para=near; podia=feet) Setae – stiff bristles on parapodia May dig them into sand for locomotion Fireworms have stinging bristles on their parapodium Polycaetes Some have a proboscis that can extend from their mouths to catch prey. Feeding organ armed with small teeth or jaws on the tip. Can make a living in many habitats: mud, sand, sponges, live corals, and algaw Tubeworms Polychaetes that live in tubes they secrete Tubes attach to rocks Feed by extending feathery tentacles Food moves along groves in tentacles to the mouth. Some retract them when food lands Use parapodia to create currents of water that flow through the tubes Aid in respiration and helps clean tubes Segmented Worms with a Coelom Annelid worms have evolved body features not found in flatworms. These features appear in some form in all larger, more complex animals: a) complete digestive system, from an anterior mouth to a posterior anus b) coelom, a body cavity between the digestive tube and the external body wall c) circulatory system consisting of a series of tubes (vessels) filled with fluid (blood) to transport dissolved nutrients, oxygen, and waste products rapidly and efficiently Segmented Worms with a Coelom Like flatworms annelids have a mesoderm with muscle, a CNS, and an Excretory system. More advanced Complete digestive system has: 1. mouth at one end, 2. a long tube with specialized parts in the middle 3. An anus at the other end. Digestive advantages Eat while previous meal digests Specialization digesting foods in stages As food move along nutrients are digested by cells. Coelom Fluid filled cavity lying between the digestive tube and outer body. Surrounded by mesoderm. Digestive tube lies inside the outer body tube “Tube within a tube construction” Fluid in the coelom: supports soft tissues of the body wall (like a cnidarins hydrostatic skeleton) Coelom Muscles in the wall of body tube and digestive tube can put pressure on the fluid to aid in movement Muscles come from mesoderm tissue. Types of muscles Circular – when contracted the segment gets longer and narrower Longitudinal – when contracted the segment gets shorter and fatter. Annelid’s CNS Found in anterior end of annelids, dorsal to digestive tube there is a pair of nerve cluster which are the brain. Nerves link the brain to sense organs Polychaetes have eyes that can detect light differences. A cluster of nerve cells called a ganglion operates the organs in each segment Annelid’s Excretory system Consists of a pair of small tubes in each segment Tubes are called nephridia (nephrus=kidney) Filter coelomic fluid which contains useful nutrient molecules along with waste molecules Annelid’s circulatory system Closed system where blood is pumped along by muscles in blood vessels. Blood flows through microscopic capillaries. Parapodia increase the surface area of the skin for respiration System allows organisms to grow large unlike flatworms.