Morgan is awesome Invertebrates (Part 2) Annelida-(Segmented Worms) The phylum Annelida are the segmented worms and are abundant in all habitats. External

Morgan is awesome Invertebrates (Part 2)

Annelida-(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 tube within-a-tube body plan known as a coelom (s 'l m) 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 Earthworms belong to this phylum. Each segment of the earthworm has setae [see-tuh] or external bristles made of chitin [kahy-tin]. 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 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 (Not all leeches suck blood).

Blood sucking leeches are collected for anticoagulant. Leeches bodies are flattened dorsoventrally and lack setae [see-tuh] except for one species. Like earthworms, leeches are hermaphrodites that exchange sperm with other members of their species.

Polychaetes Polychaetes [pol-i-keet] are marine annelids that have their setae modified into paddle-like structures called parapodia. Parapodia improve movement and give more area for gas exchange.

Polychaetes often live commensally with sponges, mollusks, echinoderms, and crustaceans. Sexes are separate with external fertilization.

Mollusca-(Mollusks) 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. Clam

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.

Gastropods 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. Snail

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. Helmet Snail

Bivalvia 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 extended from the shell for movement or anchoring.

Cephalopods The class of mollusks called cephalopods [sef-uh- luh-pod] have their muscular foot modified into tentacles on their head. Examples of cephalopods are octopus, squid and nautilus. 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. Octopus Giant Squid

Arthropoda-(Arthropods) The members of the phylum Arthropoda all have jointed appendages. The word "arthropod" means jointed leg. There are more species of arthropods than any other phylum.

Arthropod 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 [sef-uh-loh-thawr-aks], & 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 (k lis rd ) possess chelicerae or fangs and no antenna, while the subphylum Mandibulata have antenna and mandibles or jaws.

Crustaceans have pincers called chelipeds [kee-luh-ped]. 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 appendage, 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 [mal-pig- ee-uhn] tubules to filter nitrogenous wastes.

Chelicerata The subphylum Chelicerata (ki-LISS-uh- ruh) include the class Xiphosura or horseshoe crabs. Have a cephalothorax and abdomen & live in marine environments breathing through book gills. They lack antenna, but have chelicera & 4 pairs of walking legs.

Spiders The class Arachnida containing spiders, scorpions, mites, and ticks are also chelicerates that lack antenna. They have chelicera (fangs) and 4 pairs of legs. 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.

How are spiders different from insects? Spiders differ from insects in having eight, not six legs. They have simple eyes and not compound eyes. Spiders have only 2 body regions (cephalothorax & abdomen) instead of 3 regions ( head, thorax, & abdomen).

Crustaceans 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.

Cholopoda The classes Chilopoda and Diplopoda are also in the subphylum Mandibulata. Chilopoda or centipedes are poisonous predators feeding on other terrestrial arthropods.

Diplopoda 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.

Insecta 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.

Insect Mouths Grasshoppers have chewing mouthparts for eating grass. Mosquitoes have sucking mouthparts for sucking blood. Butterflies have siphoning mouthparts for getting nectar from flowers. 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. 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.

Echinodermata 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 by 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 canals 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 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. https://www.youtube.com/watch?v=4dkieg7F37c https://www.youtube.com/watch?v=A100m5EpfFI

Sea Urchins Sea urchins and sand dollars are in the class Echinoidea. They lack distinct arms. Five rows of tube feet protrude through their skeleton. 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 scrape or crush food. https://www.youtube.com/watch?v=3uwOURj neWQ https://www.youtube.com/watch?v=3uwOURj neWQ Sea Urchin Sand dollar

Sea Lilies and Feather Stars 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 stars in the class Ophiuroidea have slender arms attached to their central disk and can move faster than starfish. Sea Lily Feather Star

Sea Cucumbers 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. https://www.youtube.com/watch?v=aCxKFc3XtJs Sea Cucumber

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Morgan is awesome Invertebrates (Part 2) Annelida-(Segmented Worms) The phylum Annelida are the segmented worms and are abundant in all habitats. External