Chapter 15 Notes Invertebrates I: Sponges, Jellyfish, and Worms

Lesson A-B – Pg Invertebrates All animals are multicellular. Invertebrate – an animal without a backbone Invertebrates do not have a backbone, but they DO have a skeleton. Sponges are “pore animals”. The pores are all throughout their bodies and pump water, which brings food and oxygen in and carries waste out. The characteristic of having pores is so essential to them that the phylum was named Porifera.

Sponges Sponge skeletons are made of any of the following: spongin – a flexible, fibrous protein spicules – stiff, pointed little spikes made of calcium carbonate or silica Both Sponges are filter feeders because they filter water to obtain food. Sponges are NOT photosynthetic.

Sponges Sponges have a hollow central cavity and with a large opening at the top. The cells lining the central cavity are called collar cells, which possess flagella. The whip-like movement of the flagella causes water to flow inward so that the pores can do their jobs.

Section A-B Questions About how many animal species are there? Why is a bee considered an invertebrate? Besides bone, list three substances that could compose an animal’s skeleton. To what sponge characteristic does the phylum name Porifera refer? If adult sponges are permanently attached to solid objects, how can they colonize other areas? What and how do sponges eat?

Lesson C – Pg Jellyfish Hydrostatic skeleton – a type of skeleton with support similar to that of a water balloon. When filled, it gains shape. There are 2 layers of tissue in a jellyfish: ectoderm – outer layer of the jellyfish endoderm – inner layer that contains the gastrovascular cavity The gastrovascular cavity is where the jellyfish digests its food. Jellyfish have no brain.

Jellyfish A jellyfish swims by contracting muscles around the rim of its body. This jets water out of the gastrovascular cavity and moves the jellyfish. They do not use their tentacles for movement. A jellyfish’s tentacles have nematocysts, which are special stinging cells that penetrate an organism and release poison. Small animals can be paralyzed and killed by the poison.

Corals Corals are animals. They are in the same phylum as jellyfish – Cnidarians. Two kinds – hard corals and soft corals They both have a soft inner body called a polyp and tentacles with nematocysts. Hard corals build coral reefs. When the coral attaches itself to an object, it secretes a limestone base. When the coral dies, only the limestone base remains. When a new coral attaches itself, it secretes its own limestone base on top of the old one. As the process continues, the limestone bases stack on top of each other and accumulate into a large coral reef.

Section C Questions What is the supporting material in a jellyfish’s skeleton? Where do jellyfish digest their prey? What is the soft body of a coral animal called?

Section D Pg Planarians - Flatworm Flatworms are in the phylum Platyhelminthes. Flatworms have bilateral symmetry. Planarians (a kind of flatworm) control their bodies with their nervous system. An invertebrate’s “coordination center” is a ganglion, or simple brain, which is a collection of nervous tissue. neurons – long, thin nerve cells nerves – a collection of neurons wrapped in protective coverings

Planarians Planarians have a simple digestive system. They ingest food through their mouth, on the underside of their bodies. They suck the food into their pharynx and then into their intestine. This breaks the food down. The Planarian is only as thick as a heavy sheet of paper. This thinness allows the animal’s cells to exchange oxygen and carbon dioxide directly with the environment. It gets rid of its waste through a system of tiny tubes. At the ends of these tubes are structures called flame cells. The waste is then passed on to the excretory pores, where it is released.

Flatworms Other types of flatworms are tapeworms, flukes, and marine flatworms. Tapeworms are a common parasite of animals and humans. It is found in the digestive tract. It has a head equipped with hooks and/or suckers to attach it securely to the digestive tract. They can be unpleasant and harmful.

Section D Questions What type of symmetry does a planarian have? How many longitudinal nerves does a planarian have? Where is the mouth of a planarian?

Section E Pg.275 Roundworms Roundworms are in the phylum Nematoda. They have round, tubular bodies that are tapered at each end. Ascaris is the most common parasite in humans. Some Types: Ascaris, hookworms, pinworms, trichina, and more. These parasites are NOT beneficial to their hosts!

Section E Questions Name the phylum that includes roundworms. Where does an adult Ascaris normally live? Are roundworms parasties of animals only? Explain.

Section F Pg Segmented Worms Roundworms are in the phylum Annelida. One characteristic of the phylum Annelida that distinguishes it from other worm phyla is its segmented bodies. Some types: earthworms, leeches, tubeworms, scale worms, sandworms, fireworms, and more.

Earthworms Some earthworms can grow as long as 3 meters or 9.8 feet. The earthworm’s nervous system includes a ganglion. The digestive system: Pharynx – thick muscular walls which help to pull food into the mouth Crop – temporary storage chamber for food Gizzard – muscles contract and this begins the mechanical digestion of the food Intestine – digested food is then absorbed into the intestine where it is carried to the blood vessels. Anus – the indigestible food is then passed through the anus and released.

Earthworms The earthworm’s circulatory system is closed. In a closed circulatory system, the blood flows along the following route: veins  heart  arteries  capillaries  veins The aortic arches control the blood pressure. Earthworms do not have a respiratory system. Instead they exchange oxygen and carbon dioxide through its moist skin. The excretory includes tiny looped tubes that collect wastes from the blood. The waste collected in these tubes (excretory tubules) are passed out of the body through pores on the earthworm’s surface. Copy the diagram on book pg.280 into your journals.

Section F Questions Name three members of phylum Annelida besides earthworms. In which part of the earthworm’s digestive system does mechanical digestion occur? How does an earthworm breathe? How can our study of earthworms help us exercise dominion over the earth?