Figure 33.2 Review of animal phylogeny Ancestral colonial choanoflagellate Eumetazoa Bilateria Deuterostomia Porifera Cnidaria Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Echinodermata Chordata - Invertebrates -no backbone -95% of all animals -Tree based on body plan -Phylum Porifera (sponge) -No true tissue (parazoa) -Sessile & porous -Most are hermaphrodites Chapter 33: Invertebrates

Figure 33.4 Anatomy of a sponge Azure vase sponge (Callyspongia plicifera) Osculum Spicules Water flow Flagellum Collar Food particles in mucus Choanocyte Phagocytosis of food particles Amoebocyte Choanocytes. The spongocoel is lined with feeding cells called choanocytes. By beating flagella, the choanocytes create a current that draws water in through the porocytes. Spongocoel. Water passing through porocytes enters a cavity called the spongocoel. Porocytes. Water enters the epidermis through channels formed by porocytes, doughnut-shaped cells that span the body wall. Epidermis. The outer layer consists of tightly packed epidermal cells. Mesohyl. The wall of this simple sponge consists of two layers of cells separated by a gelatinous matrix, the mesohyl (“middle matter”). The movement of the choanocyte flagella also draws water through its collar of fingerlike projections. Food particles are trapped in the mucus coating the projections, engulfed by phagocytosis, and either digested or transferred to amoebocytes. Amoebocyte. Amoebocytes transport nutrients to other cells of the sponge body and also produce materials for skeletal fibers (spicules)

Figure 33.2 Review of animal phylogeny Ancestral colonial choanoflagellate Eumetazoa Bilateria Deuterostomia Porifera Cnidaria Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Echinodermata Chordata - Invertebrates -no backbone -95% of all animals -Tree based on body plan -Phylum Porifera (sponge) -No true tissue (Parazoa) -Sessile & porous -Most are hermaphrodites -True tissue (Eumetazoa) -Phylum Cnidaria -Radial symmetry & diploblastic -Gastrovascular cavity -1 opening - both mouth & anus -Sessile polyp or floating medusa

Figure 33.5 Polyp and medusa forms of cnidarians Mouth/anus Tentacle Gastrovascular cavity Gastrodermis Mesoglea Epidermis Tentacle Body stalk Mouth/anus Medusa Polyp

Table 33.1 Classes of Phylum Cnidaria

Figure 33.7 Cnidarians (a) These colonial polyps are members of class Hydrozoa. (b) Many species of jellies (class Scyphozoa), including the species pictured here, are bioluminescent. The largest scyphozoans have tentacles more than 100 m long dangling from a bell-shaped body up to 2 m in diameter. (c) The sea wasp (Chironex fleckeri) is a member of class Cubozoa. Its poison, which can subdue fish and other large prey, is more potent than cobra venom. (d) Sea anemones and other members of class Anthozoa exist only as polyps.

Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

Figure 33.2 Review of animal phylogeny Ancestral colonial choanoflagellate Eumetazoa Bilateria Deuterostomia Porifera Cnidaria Other bilaterians (including Nematoda, Arthropoda, Mollusca, and Annelida) Echinodermata Chordata - Invertebrates -no backbone -95% of all animals -Tree based on body plan -Phylum Porifera (sponge) -No true tissue (parazoa) -Sessile & porous -Most are hermaphrodites -True tissue (Eumetazoa) -Phylum Cnidaria -Radial symmetry & diploblastic -Gastrovascular cavity -1 opening - both mouth & anus -Sessile polyp or floating medusa -Bilateral symmetry & triploblastic -Body cavities of lophotrochozoa

Figure 32.8 Body plans of triploblastic animals Coelom Body covering (from ectoderm) Digestive tract (from endoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Pseudocoelom Muscle layer (from mesoderm) Body covering (from ectoderm) Digestive tract (from ectoderm) Body covering (from ectoderm) Tissue- filled region (from mesoderm) Digestive tract (from endoderm) Coelomate. Coelomates such as annelids have a true coelom, a body cavity completely lined by tissue derived from mesoderm. (a) Pseudocoelomate. Pseudocoelomates such as nematodes have a body cavity only partially lined by tissue derived from mesoderm. (b) Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wall. (c)

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Phylum Platyhelminthes – flat as a plate -Tapeworms & flukes -Gastrovascular cavity with 1 opening -Tapeworms absorb nutrients along the length of their body Proglottids with reproductive structures 200 µm Hooks Sucker Scolex Chapter 33: Invertebrates

Figure Anatomy of a planarian, a turbellarian Pharynx. The mouth is at the tip of a muscular pharynx that extends from the animal’s ventral side. Digestive juices are spilled onto prey, and the pharynx sucks small pieces of food into the gastrovascular cavity, where digestion continues. Digestion is completed within the cells lining the gastro- vascular cavity, which has three branches, each with fine subbranches that pro- vide an extensive surface area. Undigested wastes are egested through the mouth. Ganglia. Located at the anterior end of the worm, near the main sources of sensory input, is a pair of ganglia, dense clusters of nerve cells. Ventral nerve cords. From the ganglia, a pair of ventral nerve cords runs the length of the body. Gastrovascular cavity Eyespots

Table 33.2 Classes of Phylum Platyhelminthes

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Phylum Nematoda (round worms) Chapter 33: Invertebrates

Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Phylum Nematoda (round worms) -Mostly aquatic habitats & in body fluids & tissues -Tough transparent cuticle & unsegmented body -Complete digestive tract -Nutrients spread in fluid of pseudocoelom -Trichinella spiralis – trichinosis in undercooked meat -C. elegans 25 µm Chapter 33: Invertebrates

Figure Juveniles of the parasitic nematode Trichinella spiralis encysted in human muscle tissue (LM) 50 µm Encysted juveniles Muscle tissue

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) Chapter 33: Invertebrates

Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Muscular foot, visceral mass, mantle -Soft-bodied but most are protected by shell secreted by mantle Chapter 33: Invertebrates

Figure The basic body plan of a mollusc Visceral mass Mantle Foot Coelom Intestine Gonads Mantle cavity Anus Gill Nerve cords Esophagus Stomach Shell Radula Mouth Nephridium. Excretory organs called nephridia remove metabolic wastes from the hemolymph. Heart. Most molluscs have an open circulatory system. The dorsally located heart pumps circulatory fluid called hemolymph through arteries into sinuses (body spaces). The organs of the mollusc are thus continually bathed in hemolymph. The long digestive tract is coiled in the visceral mass. Radula. The mouth region in many mollusc species contains a rasp-like feeding organ called a radula. This belt of backward- curved teeth slides back and forth, scraping and scooping like a backhoe. The nervous system consists of a nerve ring around the esophagus, from which nerve cords extend.

Table 33.3 Major Classes of Phylum Mollusca

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Muscular foot, visceral mass, mantle -Soft-bodied but most are protected by shell secreted by mantle -Phylum Annelida – segemented worm – earthworms, leeches Chapter 33: Invertebrates

Figure One hypothesis of animal phylogeny based mainly on molecular data Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Phylum Annelida – segemented worm – earthworms, leeches -Damp climates -Divided coelom -Closed circulatory system -Digestive tract with specialized regions -Ventral nerve cord & cerebral ganglia Chapter 33: Invertebrates

Figure Anatomy of an earthworm Mouth Subpharyngeal ganglion Pharynx Esophagus Crop Gizzard Intestine Metanephridium Ventral vessel Nerve cords Nephrostome Intestine Dorsal vessel Longitudinal muscle Circular muscle Epidermis Cuticle Septum (partition between segments) Anus Each segment is surrounded by longitudinal muscle, which in turn is surrounded by circular muscle. Earthworms coordinate the contraction of these two sets of muscles to move (see Figure 49.25). These muscles work against the noncompressible coelomic fluid, which acts as a hydrostatic skeleton. Coelom. The coelom of the earthworm is partitioned by septa. Metanephridium. Each segment of the worm contains a pair of excretory tubes, called metanephridia, with ciliated funnels, called nephrostomes. The metanephridia remove wastes from the blood and coelomic fluid through exterior pores. Tiny blood vessels are abundant in the earthworm’s skin, which functions as its respiratory organ. The blood contains oxygen-carrying hemoglobin. Ventral nerve cords with segmental ganglia. The nerve cords penetrate the septa and run the length of the animal, as do the digestive tract and longitudinal blood vessels. The circulatory system, a network of vessels, is closed. The dorsal and ventral vessels are linked by segmental pairs of vessels. The dorsal vessel and five pairs of vessels that circle the esophagus of an earthworm are muscular and pump blood through the circulatory system. Cerebral ganglia. The earthworm nervous system features a brain-like pair of cerebral ganglia above and in front of the pharynx. A ring of nerves around the pharynx connects to a subpharyngeal ganglion, from which a fused pair of nerve cords runs posteriorly. Chaetae. Each segment has four pairs of chaetae, bristles that provide traction for burrowing. Many of the internal structures are repeated within each segment of the earthworm. Giant Australian earthworm Clitellum

Table 33.4 Classes of Phylum Annelida

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Phylum Annelida – segemented worm – earthworms, leeches -Damp climates -Divided coelom -Closed circulatory system -Digestive tract with specialized regions -Ventral nerve cord & cerebral ganglia -Phylum Arthropoda – jointed feet – insects, spiders, crustaceans Chapter 33: Invertebrates

Figure One hypothesis of animal phylogeny based mainly on molecular data Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Phylum Annelida – segemented worm – earthworms, leeches -Phylum Arthropoda – jointed feet – insects, spiders, crustaceans -Regional segmentation & jointed appendages -Appendages for walking, eating, copulating, defense, sensing -Exoskeleton of chitin & proteins – molts -Extensive cephalization -Open circulatory system Chapter 33: Invertebrates

Figure External anatomy of an arthropod Antennae (sensory reception) Head Thorax Swimming appendages Walking legs Mouthparts (feeding) Pincer (defense) Abdomen Cephalothorax

Table 33.5 Subphyla of Phylum Arthropoda

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Phylum Annelida – segemented worm – earthworms, leeches -Phylum Arthropoda – jointed feet – insects, spiders, crustaceans -Insects -Most have wings – 1 or 2 pair -Malpighian tubules remove waste from hemolymph -Tracheal system for gas exchange -Ventral nerve cords -Incomplete of complete metamorphosis -Pollination & crop destruction -Disease carriers Chapter 33: Invertebrates

Figure Anatomy of a grasshopper, an insect Compound eye Antennae Anus Vagina Ovary Dorsal artery Crop Abdomen Thorax Head The insect body has three regions: head, thorax, and abdomen. The segmentation of the thorax and abdomen are obvious, but the segments that form the head are fused. Heart. The insect heart drives hemolymph through an open circulatory system. Cerebral ganglion. The two nerve cords meet in the head, where the ganglia of several anterior segments are fused into a cerebral ganglion (brain). The antennae, eyes, and other sense organs are concentrated on the head. Tracheal tubes. Gas exchange in insects is accomplished by a tracheal system of branched, chitin-lined tubes that infiltrate the body and carry oxygen directly to cells. The tracheal system opens to the outside of the body through spiracles, pores that can control air flow and water loss by opening or closing. Nerve cords. The insect nervous system consists of a pair of ventral nerve cords with several segmental ganglia. Insect mouthparts are formed from several pairs of modified appendages. The mouthparts include mandibles, which grasshoppers use for chewing. In other insects, mouthparts are specialized for lapping, piercing, or sucking. Malpighian tubules. Metabolic wastes are removed from the hemolymph by excretory organs called Malpighian tubules, which are out- pocketings of the digestive tract.

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelomates -Coelomates -Phylum Mollusca (snails, clams, oysters, octopus, etc) -Phylum Annelida – segemented worm – earthworms, leeches -Phylum Arthropoda – jointed feet – insects, spiders, crustaceans -Insects -Most have wings – 1 or 2 pair -Malpighian tubules remove waste from hemolymph -Tracheal system for gas exchange -Ventral nerve cords -Incomplete or complete metamorphosis -Significant ecological impact -Pollination & crop destruction -Disease carriers -Deuterostomes Chapter 33: Invertebrates

Figure One hypothesis of animal phylogeny based mainly on molecular data Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Mollusca Annelida Rotifera Nematoda Arthropoda “Radiata” “Porifera” DeuterostomiaLophotrochozoaEcdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagellate

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelmates -Coelomates -Deuterostomes -Phylum Echinodermata –spiny skin – sea urchin, sea stars, -Sessile or slow movers as adults -Radial symmetry Chapter 33: Invertebrates

Figure Echinoderms (a) A sea star (class Asteroidea) (b) A brittle star (class Ophiuroidea) (c) A sea urchin (class Echinoidea) (d) A feather star (class Crinoidea) (e) A sea cucumber (class Holothuroidea) (f) A sea daisy (class Concentricycloidea)

- Invertebrates -True tissue (Eumetazoa) -Bilateral symmetry -Body cavities of lophotrochozoa -Acoelomates -Pseudocoelmates -Coelomates -Deuterostomes -Phylum Echinodermata –spiny skin – sea urchin, sea stars, -Sessile or slow movers as adults -Radial symmetry -Phylum Chordata – Ch 34 - vertebrates Chapter 33: Invertebrates

Table 33.7 Selected Animal Phyla