Invertebrate+Notes


 * // Invertebrate Notes  //**

// **Invertebrate Phyla:**  // |||||||||||||||||||||||| ** Porifera **-sponges |||| ||||||||||  ||
 * [[image:http://www.biologyjunction.com/images/spawning_sponge1.jpg width="122" height="179" align="center"]]
 * [[image:http://www.biologyjunction.com/images/spawning_sponge1.jpg width="122" height="179" align="center"]]
 * ** Cnidaria:  ** ||
 * [[image:http://www.biologyjunction.com/images/DSCN05831.jpg width="126" height="146" align="center"]]

sea anemone |||||||||| hydra |||||||||| Coral || Jellyfish ||
 * ** Platyhelminthes **-flatworms ||
 * [[image:http://www.biologyjunction.com/images/fluke1.gif width="180" height="60" align="center"]]

Fluke |||||||||||| Tapeworm ||
 * ** Nematoda **-roundworms ||
 * [[image:http://www.biologyjunction.com/images/trichinella-adult-chmai1.jpg width="154" height="116" align="center"]]

//Trichinella// ||||||||

//Ascaris// ||||||||

H ookworms ||||

Pinworms || earthworm |||||||||||| leech || clam |||||||| snail |||||||| octopus || Trilobite |||||||| Horseshoe crab |||||||| Millipede || Starfish |||||||| Sea Cucumber |||||||| Sea Lily || About **97%** of all animals are invertebrates. Invertebrates are animals which **do not have a backbone**. There are **nine phyla** of invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Rotifera, Mollusca, Annelida, Arthropoda, & Echinodermata. **Sponges** The phylum ** Porifera ** are sponges. There are about ** 800 different species ** of sponges, and ** 88% are marine **. "Marine" means that they live in salt water, such as an ocean or a sea. ** Freshwater sponges ** are smaller and less brightly colored than marine sponges. Sponges are ** filter feeders **. This means that they use their body as a filter to trap their food,** microscopic plankton **. Sponges are ** asymmetrical ** and live attached to one spot as adults making them ** sessile ** animals. Sponges have a skeleton composed of a flexible protein material called ** spongin ** & hard fibers called ** spicules ** composed of calcium carbonate or silicon dioxide. The body of a sponge is filled with ** holes or pores ** through which water enters their ** hollow bodies **. Sponges ** lack the tissue level ** of organization but they do have some specialized cells. ** Choanocytes ** are specialized cells that line pores in a sponge and have a **flagellum** that spins to pull in water and food. ** Collar cells ** at the base of choanocytes capture plankton & start digesting it. **Amebocytes** are specialized cells that carry food to all other parts of a sponge's body. Wastes and excess water leave a sponge through an opening at the top called the ** osculum **. Sponges reproduce asexually by internal or external ** buds ** and by ** fragmentation ** whenever a piece of the sponge breaks off. Each piece can form a new sponge. This is how sponges form ** colonies **. Sponges are **hermaphrodites** that produce both eggs and sperm. They do not fertilize their own eggs, but they **exchange sperm** with other sponges. Sponges reproduce sexually by dispensing eggs and sperm into the water. If the freshwater supply evaporates, freshwater sponges become dormant and form an internal bud or ** gemmule ** which is release when the sponge dies. The gemmule is a small freshwater sponge covered with hardened mucus which prevents it from drying out. When the freshwater returns, the gemmule becomes an **active** sponge **Cnidarians** T he phylum Cnidaria include ** sea anemones, hydra, corals and jellyfis ** h. All Cnidaria are **marine except hydra**, which is a freshwater organism. Cnidarians have ** radial symmetry ** and are ** carnivorous ** using **tentacles** that surround their **mouth** to get food. Cnidarians exhibit two body forms - the sessile ** polyp ** with tentacles & mouth at the top or the motile** medusa ** with tentacles & mouth on the bottom. Cnidarians may exist in one of these two stages or go through both stages in their life cycle such as the jellyfish. Cnidarians have 2 layers of cells --- ** gastrodermis & epidermis **. Cnidarians have a hollow ** gastrovascular cavity ** on the inside lined with ** gastrodermis **. ** Epidermis ** covers the outside and a jellylike material called ** mesoglea ** is between the layers. **Mesoglea is thin in polyp** forms but **thick in medusa forms**. Cnidarians have stinging cells called ** nematocysts or cnidocytes ** on their tentacles that are **poisonous** & shoot out like a** harpoon ** to kill or **paralyze prey**. Their ** mouth ** is the only opening to their body so they have a **two-way** **digestive system**. The also have a simple ** nerve net **. Cnidarians reproduce ** asexually by budding ** or **sexually** producing fertilized eggs whenever males release sperm and females release eggs into the water. Some cnidarians like ** coral build a limestone case ** that makes an underwater **reef.** **Platyhelminthes (flatworms)** The phylum Platyhelminthes are ** dorsoventrally flattene d** and have a definite anterior and posterior end giving them** bilateral symmetry **. Their bodies are solid so they are said to be ** acoelomate **. Some flatworms are ** parasites **, while others are **free-living** carnivores or scavengers. Examples of parasitic flatworms are ** flukes and tapeworm **s. Flatworms also have only a ** mouth ** for both food and wastes. Their nervous system is composed of a ** nerve net ** and sometimes light-sensitive ** eyespots ** at the anterior end. Specialized ** flame cells ** help get rid of wastes. The ** planarian **is the most common free-living flatworm found in ** water or moist places **. They are ** hermaphrodites ** producing both eggs and sperm, but they ** exchange sperm ** with each other during sexual reproduction. Planarians also reproduce asexually by ** fragmentation **. Flukes and tapeworms often live in their ** host's digestive tract ** resistant to the ** host's enzymes. ** They do not have a digestive system allowing the ** host to digest their food. ** Tapeworms are divided into sections called ** proglottids ** that each have a complete reproductive system producing fertilized eggs. Tapeworms are ** hermaphroditic ** (one body having both sexual parts), and they ** fertilize their own eggs **. **Ripe proglottid** s with their eggs pass out with the host's feces. Tapeworms anterior end is called the ** scolex ** and is modified with both **hooks and suckers** to attach to the host's intestines. Humans most often get tapeworms from i **nfected, undercooked pork, beef. or fish**. Tapeworm eggs can withstand boiling water so it is important to cook these meats well enough to destroy the eggs. Children sometimes get tapeworms by playing with the ** feces in the litter box of a cat **, getting the eggs on their hands, and placing their hands or fingers in their mouth. The longest tapeworm ever passed by a person was **39 meters**. Flukes have complex life cycles that involve ** more than one host **. A fluke causes ** Schistosomiasis **, a disease that affects 250 million people world wide. This blood fluke attacks the kidneys, liver, and intestines causing progressive weakness. It often takes 20 years to die from Schistosomiases, & there is no cure. **Nematoda (roundworms)** The phylum Nematoda are the **roundworms**. Roundworms are **cylindrical in shape, tapered at both ends,** and vary in length from being microscopic to 20 inches long. Roundworms are ** pseudocoelomate ** having a body cavity that is not completely lined. The body cavity or ** pseudocoel ** serves as a ** hydrostatic skeleton ** against which ** muscles ** can contract. Unlike flatworms, roundworms have a complete gut. This means that they have a ** one-way digestive trac t** with a gut that begins with a ** mouth ** and ends with an ** anus **. Therefore, they are usually ** able to digest food **. However, roundworms have **no blood or heart**. Nutrients are distributed by a non-blood fluid which is not pumped. Most roundworms are ** parasites ** and are found in ** all habitats **. They are ** bilaterally symmetrica **l and ** unsegmented **. Although they are cylindrical in shape, they usually taper at both ends. They are covered with a thick protective ** cuticle ** that is flexible and can be molted. They have ** separate sexes ** generally and reproduce sexually. The roundworm // **Trichinella** //, causes the disease called **trichinosis**. People get trichinosis from eating infected, undercooked pork. Trichinella gets into muscles and ** leaves calcium deposits ** which effect muscle contraction. Trichinosis can affect the heart. Another roundworm, //** Ascaris **//, parasitizes human lungs. The // **Filaria** // worm attacks the ** lymphatic system ** causing great swelling. **Hookworms** and ** pinworms ** are also roundworms which parasitize humans. **Rotifers** The phylum ** Rotifera ** includes ** microscopi **c worms found in **aquatic and soil habitats**. They have a ** crown of cilia ** at their head end surrounding their mouth for movement and feeding. Their bodies are covered with an external layer of** chitin .** Having ** separate sexes **, they reproduce sexually. **Some species contain only females** and reproduce by** parthenogenesis ** (unfertilized eggs developing into females). The phylum **Mollusca** contains ** snails and slugs, bivalves, octopus, squid, and the chambered nautilus **. Many members of this phylum have durable ** limestone shells ** and are found in ** all habitats **. Members of this group are** economically important ** as sources of human food, pearl and shell production, crop & flower damage, destruction to submerged wooden structures, and intermediate hosts for some parasitic diseases. The ** giant squid and giant clam **are the two largest invertebrates. Mollusks have ** bilateral symmetry ** and a ** visceral mass ** containing their body organs. Mollusks also have a ** muscular foot ** for movement which can be modified into **arms or** **tentacles** in some species. Mollusks breathe through ** gills or lungs ** located below a protective layer called the ** mantle **. The mantle forms the shell in some species and also protects the body organs. All mollusks except bivalves contain a rasping, tongue-like ** radula ** for scraping food. The circulatory system consists of a ** three-chambered heart ** and ** open-flowing system ** except for octopus & squids which have a ** closed circulatory system **. Reproduction is sexual even in hermaphroditic forms. Mollusks go through a free swimming larval stage called the ** trochophore .** The class of mollusks called **gastropods** have a foot on their belly. An example of a gastropod is the ** snail **. When a snail lacks a shell it is called a ** slug **. Snails and slugs walk on their belly. Most snails are marine, but some do live on land. Marine snails have ** gills **. Land snails are called **pulmonate** snails and have an ** air hole ** for breathing. Snails can be very large. The ** helmet snail **can be as big as 15 pounds. The class of mollusk called ** Bivalvia ** includes ** clams, oysters, mussels, and scallops **. These mollusks have ** two shells hinged together by a ligament **. Strong **adductor** **muscles** open and close the shells. Incurrent and excurrent ** siphons **circulate water containing food and oxygen through the bivalve. ** Gills ** extract the oxygen from the water, and they move by ** jet propulsion **. Their muscular foot can be extende d from the shell for movement or anchoring. The class of mollusks called ** cephalopods ** have their muscular foot modified into tentacles on their head. Examples of cephalopods are ** octopus, squid and nautilus **. Most cephalopods have ** beaks **, **tentacles** and jaws and are active **predators**. Their muscular foot has been modified into ** arms or tentacles **. They **lack external shells** except for the** nautilus **. These are the most intelligent of all invertebrates. They used their siphons to move by **jet propulsion**. Octopus have their shell inside of their body. Octopus secrete an ** inky substance ** which they spit out to help them escape from predators. The ** giant squid ** is the largest cephalopod. It can be up to 60 meters in length and has been known to eat whales. **Annelids (segmented worms)** The phylum Annelida are the ** segmented worms ** and are abundant in **all habitats**. External segments are characterized by ringlike structures called ** metameres ** along the body, and corresponding internal segments are called ** septa **. ** Segmentation ** gives worms more flexibility in movement. If one segment is damaged, it isn't usually fatal to the animal because their organs are duplicated in other segments. Annelids have a A ** tube within-a-tube ** body plan known as a** coelom ** which is fully lined and contains the body organs. The coelom runs from the **mouth to the anus**. Annelids have** bilateral symmetry **, and a ** well-developed brain **and diverse sense organs showing **cephalization**. ** Coelomic fluid ** serves as a ** hydrostatic skeleton **. Earthworms belong to this phylum. Each segment of the earthworm has ** setae ** or external bristles made of ** chitin **. These bristles allow the earthworm to move and to burrow into soil. Earthworms have a head and a central nervous system. Earthworms respire through their ** moist skin **as they dig through the soil and help loosen it. They have a ** closed circulatory system ** in which blood is pumped by ** five pairs of hearts **. Most earthworms feed on decomposing vegetation causing it to decompose faster. A ** pharynx ** sucks in the organic debris which the muscular ** gizzard ** grinds. Earthworms bring the nutrients from the subsoil to the top soil, thereby helping plants to grow. Undigested materials or ** castings ** are deposited outside burrows. ** Leeches **are also in the phylum Annelida. Most leeches live in water and have ** suckers ** at both ends of their bodies. The** tail suckers ** are used to latch on to a host, while the ** head suckers ** are used to suck blood from the host. Most leeches are **predators** or ** scavengers **, but ** some suck blood **. Because of this, blood sucking leeches are collected for** anticoagulant **. Leeches bodies are **flattened dorsoventrally** and ** lack setae **except for one species. Like earthworms, leeches are ** hermaphrodites ** that **exchange sperm** with other members of their species. **Polychaetes** are ** marine ** annelids that have their setae modified into paddle-like structures called ** parapodia **. Parapodia improvement movement and give more area for gas exchange. Polychaetes often live ** commensally ** with sponges, mollusks, echinoderms, and crustaceans. **Sexes are separate** with external fertilization. **Arthropods** The members of the phylum ** Arthropod **a all have ** jointed appendage s**. In fact, the word "arthropod" means jointed leg. There are more species of arthropods than any other phylum. **//Arthropods have these characteristics://** a. hard **exoskeleton** which is usually composed of substance called **chitin** b. go through **periodic ecdysis** (molting) as they shed or molt their exoskeleton c. they have specialized ** body segments ** (head, thorax, cephalothorax, & abdomen) d. **jointed appendages** such as legs, antenna, and mouthparts. e. ** open circulatory system ** (blood is pumped out of blood vessels into the body) The phylum ** Arthropoda ** is divided according to their type of **appendages**. The subphylum ** Chelicerata **possess** chelicerae ** or fangs and no antenna, while the subphylum __** Mandibulata **__ have antenna and ** mandibles ** or jaws. **Crustaceans** have pincers called ** chelipeds **. The subphylum __** Trilobita **__ are an extinct group with a head and trunk with a pair of legs on each segment. **Terrestrial** arthropods like ** insects, millipedes, & centipedes ** have a system of hollow air tubes called** tracheae ** as their respiratory system. ** Aquatic chelicerates ** like the **horseshoe crab** have ** book gills, ** while ** terrestrial chelicerates ** such as **spiders, ticks, mites, & scorpions** use ** book lungs **. Book lungs have numerous blood vessel lined surfaces which look like the pages in a book & get oxygen from air. Crustaceans respire through ** gills **. Gills are folded tissue which are lined with blood vessels which remove oxygen from water. ** Terrestrial mandibulates ** are** uniraimous ** with one-branched appendages, but ** aquatic mandibulates ** like crustaceans are ** biramous ** or two-branched. Arthropods have a brain and nervous system and possess a variety of sensory receptors such as simple eyes called** ocelli ** or compound eyes, ** tympanic membranes ** for hearing, and **antenna** that can smell and taste. Excretory structures in arthropods vary, but terrestrial arthropods have ** Malpighian tubules ** to filter nitrogenous wastes. The subphylum **Chelicerata** (ki-LISS-uh-ruh) include the class __ **Xiphosura** __ or horseshoe crabs which have a **cephalothorax** and **abdomen**, live in ** marine ** environments breathing through book gills, lack antenna, but have chelicera & 4 pairs of walking legs. The class __** Arachnida **__ containing spiders, scorpions, mites, and ticks are also chelicerates that lack antenna, have ** chelicera (fangs) ** and 4 pairs of legs, but they live in terrestrial habitats and breathe through book lungs or trachea. Chelicerates also have appendages on their head called ** pedipalps ** that are sensory and can help move food into their mouth. Unlike most arthropods, **spiders** do not see well; however, they are good at detecting movement. Spiders have glands called ** spinnerets ** on the posterior end of their abdomen that produce **silk** to make webs. When prey get caught in a spider's web, it is the movement which alerts the spider to the captured prey. Most spiders also have hairs on their body to assist them in feeling movement. Spiders ** poison ** their prey once they are caught in their webs. Spiders are very beneficial because they catch and eat insects. Two spiders which are dangerous are the ** black widow ** and the ** brown recluse **. Both of these spiders have distinct markings on the underside of their abdomen. Spiders differ from insects in having eight, not six legs, having ** simple eyes ** and not compound eyes, and having only **2 body regions (cephalothorax & abdomen)** instead of 3 regions ( head, thorax, & abdomen). The subphylum ** Mandibulata ** contains the class __Crustacea__. Most crustaceans live in the water and include ** crabs, shrimp, lobster, crayfish, & barnacles **. Terrestrial crustaceans include ** pillbugs and sowbugs **. Crustaceans have a pair of ** antenna ** to smell and detect chemicals and a shorter pair of ** antennules ** used for balance. They have 2 body regions (cephalothorax and abdomen), and their mouthparts include ** mandibles, maxilla, and maxillipeds **. They also have pincers called ** chelipeds ** to help them catch food. Aquatic crustaceans have a shell called a **carapace** that they regularly shed as they grow to produce a larger one. Crustaceans are economically important to man as a food source. The classes ** Chilopoda ** and ** Diplopoda ** are also in the subphylum **Mandibulata**. **Chilopoda** or ** centipedes ** are ** poisonous predators ** feeding on other terrestrial arthropods. Centipedes have fangs, venom glands, and a pincer on their tail. They have a single pair of legs per body segment. ** Diplopoda ** or ** millipedes ** are **vegetarians** or scavengers feeding on decaying vegetation that have two pairs of legs per body segment. The class ** Insecta ** in the subphylum **Mandibulata** includes all of the insects. This is the ** largest and most successful group ** of arthropods. Insects usually have **six legs**, a ** pair of antenna **, and a ** pair of wings ** although some species may be wingless such as silverfish and termites. Flies have their second pair of wings modified into a balancing structure called ** halteres **. Insect's mouths usually have four parts - the ** mandible ** or **jaw, maxilla, labium or lower lip, and labrum or upper lip** and are adapted for a particular food. For example, grasshoppers have **chewing** mouthparts for eating grass, mosquitoes have ** sucking ** mouthparts for sucking blood, butterflies have ** siphoning ** mouthparts for getting nectar from flowers, and the house fly has ** spongy ** **mouth parts** for soaking up liquid food. **Wings and legs are attached to the midsection** or ** thorax **, antenna, eyes, and mouthparts are attached to the head, and the abdomen on females may have an egg-laying tube called the ** ovipositor **. Insects communicate by producing sounds and by making chemicals called ** pheromones .** ** Tympanic membranes ** on the abdomen and ** sensory hairs ** detect sound waves. ** Spiracles **line the sides of the insect's abdomen and open into their breathing tubes or trachea. Insects may go through stages** (metamorphosis) ** in their life cycle. Butterflies, bees, flies, and beetles go through the **egg, larva, pupa, and adult stages**. This is known as **complete** **metamorphosis**. Dragonflies and grasshoppers go through ** egg, nymph, and adult stages ** known as ** incomplete metamorphosis **. Insects such as silverfish and fleas do not go through metamorphosis. Metamorphosis and molting are controlled by ** hormones **. The phylum **Echinodermata** include the **starfish, sea urchins and sea cucumbers**. The word "echinoderm" means ** spiny skin **. Echinoderms are the most advanced invertebrates. All other invertebrates are ** protostomes ** in which the **blastopore (first opening in embryo)** in their development ** becomes the mouth **. Echinoderms, like chordates, are** deuterostomes ** in which the ** blastopore becomes the anus **. Echinoderms have an ** endoskeleton ** composed of movable or fixed calcium plates called ** ossicles **. The members of this phylum have ** radial symmetry ** with a ** five part body plan ** **(pentaradial)**. Adults have **no head or brain** and move be extendable ** tube feet **. Echinoderms also possess a ** water vascular system ** made up of a system of canals that help the organism feed and move. Water enters through an opening called the **madreporite** into a short ** stone canal ** into the **ring** **canal**. ** Radial canal s** connect to the ring canal and determine the five-part symmetry. This hydraulic water system is strong enough to help starfish open clam shells. ** Skin gills ** are used for respiration and waste removal. Echinoderms are capable of extensive ** regeneration ** whenever parts are dropped. They can reproduce asexually by ** fragmentation ** or sexually with external fertilization. Starfish are in the class ** Asteroidea ** and are **active marine predators** with 5 arms set off from a ** central disk ** and their mouth located on the underside or ** oral surface **. ** Bivalve mollusks ** are a favorite food of the starfish, and they consume them by ** turning their stomach inside out **and sticking it into the clam shell to digest the clam. ** Sea urchins and sand dollars ** are in the class ** Echinoidea ** and they **lack distinct arms.** Five rows of tube feet protrude through their skeletal. They use the spines of their skin and tube feet to move about and ** graze on algae, coral, or dead fish **. ** Triangular teeth ** around the mouth scrap or crush food. The class ** Crinoidea ** contains ** sea lilies and feather stars ** with ** highly branched arms ** around their mouth for ** filter feeding **. Sea lilies are ** attached by a stalk ** to the substrate, but feather stars are able to detach and move about. ** Brittle star **s in the class ** Ophiuroidea ** have ** slender arms ** attached to their central disk and **can move faster than starfish**. ** Sea cucumbers **are in the class ** Holothuroidea **and are soft, sluglike organisms with **leathery outer skin**. Sea cucumbers usually lie on their sides on the ocean bottom and ** can eject part of their intestines ** in order to scare away a predator. They also move by tube feet or by wiggling their entire body. Some of these are ** hermaphroditic ** which is unusual for echinoderms.
 * ** Rotifera **--rotifers ||
 * [[image:http://www.biologyjunction.com/images/rader1.jpg width="212" height="157" align="center"]] |||||||||||| [[image:http://www.biologyjunction.com/images/rotif2b1.jpg width="96" height="153" align="center"]] ||
 * ** Annelida **-segmented worms ||
 * [[image:http://www.biologyjunction.com/images/earthworm_on_sidewalk1.jpg width="195" height="145" align="center"]]
 * ** Mollusca  ** ||
 * [[image:http://www.biologyjunction.com/images/clam1.jpg width="165" height="193" align="center"]]
 * ** Arthropoda  ** ||
 * ** Subphylum: Trilobita ** --trilobites (extinct) |||||||| ** Subphylum: Chelicerata  ** -horseshoe crabs, spiders, scorpions, mites, & ticks |||||||| **Subphylum: Mandibulata **--crustaceans, insects, millipedes, centipedes ||
 * [[image:http://www.biologyjunction.com/images/images14.jpg width="148" height="97" align="center"]]
 * ** Echinodermata :** starfish, sea cucumbers, sea lilies ||
 * [[image:http://www.biologyjunction.com/images/Copy_of_starfish1.jpg width="150" height="150" align="center"]]
 * Mollusks **
 * Echinoderms **