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 knownfor 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, amantle, 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 coelomateswith exoskeletons and jointed appendages.

-Population: 1 billion billion (1018)-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. MillipedesBody with distinct head bearing antennaeand chewing mouthparts, segmented bodywith two pairs of walking legs per segment;terrestrial and herbivorous.

-Chilopods: Ex. CentipedesBody with distinct head bearing largeantennae and 3 pairs of mouthparts; appendages of first body segment modified as poison claws; body segmentsbear 1 pair of walking legs each; terrestrial; carnivorous.

-Insecta: Ex. InsectsBody divided into head, thorax, and abdomen; antennae present; mouthpartsmodified for chewing, sucking, or lapping;usually with two pairs of wings and threepairs 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 pairsof 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