Ch. 33: Invertebrates (Animals without a backbone)

1.Phylum Porifera: Sponges -Sessile (attached to bottom) -Spongocoel (central cavity) -Osculum (large opening) -Choanocytes (flagellated collar cells) -Hermaphroditic (produce both sperm and eggs)

2.Phylum Cnidaria: hydras, jellyfish, sea anemones, and coral animals. -Diploblastic -Radial symmetry -Gastrovascular cavity (sac with a central digestive cavity) -Nerve net -Hydrostatic skeleton (fluid held under pressure) -Polyps and medusa -Cnidocytes (cells used for defense and prey capture) -Nematocysts (stinging capsule)

3.Phylum Ctenophores: Comb jellies -8 rows of comblike plates of fused cilia (largest animals that use cilia for locomotion) -Tentacles with colloblasts (adhesive structures that capture prey)

4.Phylum Platyhelminthes: Flatworms -Reproduce asexually via regeneration -Reproduce sexually; hermaphorditic cross-fertilization - Bilateral; no body cavity -Predators, scavengers, parasites -Triplobastic; mesoderm but, GVC with only one opening – pharynx -Some cephalization – ganglia, eyespots -Many pathogens (Schistosoma, Cestodidias)

5.Phylum Rotifera: are pseudocoelomates with jaws, crowns of cilia, and complete digestive tracts. -1,800 species, are tiny animals (0.05 to 2 mm), most of which live in freshwater. -Internal organs in the pseudocoelomates. -Pseudocoelomate acts as a hydro- static skeleton & circulatory system. -Some only exist as females, reproducing more females from unfertilized eggs (parthogenesis)

6.Phylum Lophophorate: Bryozoans, Phoronids, and Brachipods. -Molecular data shows that lophophorates are protostomes. -Named Lophophores as they all have a common physical feature: the lophophore.  The lophophore is a horse-shoe-shaped or circular fold of the body wall bearing ciliated tentacles that surround the mouth.

7.Phylum Nemertea: Proboscis worms known for the prey-capturing apparatus. -Resemble flatworms like tapeworms, but have fluid-filled sacs that resemble a true coelom. -Sometimes called “ribbon worms” -Have complete digestive and circulatory system. -Proboscis sticky, barbed, or poisonous

8.Phylum Mollusca have a muscular foot, a mantle, and a visceral mass. -Slugs, snails, oysters, clams, octopus, and squids. -Marine and freshwater -Soft bodied with hard shell; slugs, octopus, and squids have lost or reduced during their evolution.

-Foot: used for locomotion -Visceral mass: contains the organs -Mantle: secretes the shell -Radula: used to scrape up food

-Most mollusks are separated sexes, but some snails are hermaphrodites. -The life cycle of many mollusks include a ciliated larva called a trophophore (also in Annelids). -8 classes: 1. Polyplacophora (chitons), 2. Gastropoda (snails and slugs), 3. Bivalvia (clams, oysters, and other bivalves), and 4. Cephalopoda (squids, octopuses, and nautiluses).

-Unique among the mollusks, the cephalopods have a well-developed brain and nervous system. -They also have a closed circulatory system.

9.Phylum Annelids: Segmented worms -Septa between the segments. -Digestive system -Closed circulatory system -Each segments contains a metanephridia, which excretes wastes  Wastes excreted out through pores. - Two brain-like ganglia in head -Hermaphrodites -Some can reproduce asexually by fragmentation and then regeneration

-3 Classes: 1. Oligochaeta (earthworms) 2. Polychaeta (marine segmented worms) 3. Hirudinea (leeches) Polychaeta Leech

10.Phylum Nematodes: Roundworms are non- segmented pseudocoelomates covered by a tough cuticle. -90,000 species (with probably 10x more) -Size: 1mm to more than 1m -Lack a circulatory system -Complete digestive tract -Move by moving back and forth due to longitudinal muscles -Reproduce sexually with internal fertilization -Female can lay over 100,000 eggs

11.Phylum Arthropods: Segmented coelomates with exoskeletons and jointed appendages. -Population: 1 billion billion (10 18 ) -Nearly 1 million species (most successful animal phylum)

-The exoskeleton is made up of chitin and protein. a. Provides protection b. Provides points of attachment for the muscles that move appendages -The animal must molt (ecdysis) its old exoskeleton if it outgrows it. -Well-developed eyes, olfactory receptors, and antennae for touch and smell (most at the anterior end = cephalization). -Open circulatory system: Hemolymph (the word “blood” is reserved for a closed circulatory system) is pumped from the heart into spaces surrounding tissue and organs.

-Some major classes in phylum arthropods: Arachnids: Ex. Spiders, scorpions, ticks, mites Body with 1 or 2 main parts, six pairs of appendages (Chelicerae, pedipalps, and 4 pairs of walking legs); mostly terrestrial.

-Diplopods: Ex. Millipedes Body with distinct head bearing antennae and chewing mouthparts, segmented body with two pairs of walking legs per segment; terrestrial and herbivorous.

-Chilopods: Ex. Centipedes Body with distinct head bearing large antennae and 3 pairs of mouthparts; appendages of first body segment modified as poison claws; body segments bear 1 pair of walking legs each; terrestrial; carnivorous.

-Insecta: Ex. Insects Body divided into head, thorax, and abdomen; antennae present; mouthparts modified for chewing, sucking, or lapping; usually with two pairs of wings and three pairs of legs; mostly terresterial. -complete digestive system. -Open circulatory system (hemolymph) -Metabolic wastes removed from the hemolymph via the excretory organs called Malpighian tubules. -Gas exchange via the the trachael system open to the outside through spiracles (pores).

-Crustaceans: Ex. Crabs, lobsters, and shrimp. Two pairs of antennae, three or more pairs of appendages. Walking legs in the thorax, and abdomen. Appendages can be regenerated if lost. -Isopods: Largest group of crustaceans (about 10,000 species) Marine and terrestrial Examples: Pill bugs

-Phylum Echinodermata: Sea stars, sea urchins, sea cucumbers. Mostly sessile or slow-moving Parts of the animal radiate out from the center, usually as 5 spokes.

-Sexual reproduction: males and females that release egg and sperm into the seawater. -Radial adults develop from bilateral larvae. (Hence, the echinoderms belonging to the bilateral branch.) -Radial adults are not truly radial as a sea star’s water vascular system is not central, but to one side.

-6 Classes in Phylum Echinoderms: 1.Asteroidea: Sea stars 2.Ophiuroidea: Brittle stars 3.Echinoidea: Sea urchins and sand dollars 4.Crinoidea: Sea lilies and feather stars 5.Holothuroidea: Sea cucumbers 6.Concentricycloidea: Sea daisies