Invertebrates By: Ryan, Rachael and Darrin

Sample Organisms Some sample organisms are … Jellyfish Grasshoppers Sea anemone Earth worm Sea sponge Spiders Flatworm Hydra

Habitat of Invertebrates Since all invertebrates rely on aerobic respiration, they cannot survive in places without oxygen. They can live anywhere oxygen is available. It is very hard for most invertebrates to survive in cold weather.

Characteristics of Invertebrates Invertebrates don't have an internal skeleton or back bone. Many invertebrates have a fluid-filled, hydrostatic skeleton. Others have a hard outer shell, like insects and crustaceans. Heterotrophic No cell walls Eukaryotic

How are invertebrates further classified? The animal kingdom is split up into vertebrates and invertebrates Invertebrates are split up into 34 different phylum including Porifera (sponges) Cnidarian (jellyfish) Platyhelminthes (flatworms) Nematoda (roundworms) Echinoderm (starfish) Molluska ( clams) Annelida (segmented worm) Arthropoda ( spiders)

Labelled Diagram of the Jellyfish

Jellyfish Nervous System The jellyfish has a nervous system characterized by a series of interconnected nerve cells (a nerve net). The nerve net conducts impulses around the entire body of the jellyfish. The strength of a response is equal to the stimulus strength. In other words, the stronger the stimulus, the larger the response. The jellyfish lack a true organ system they have no real nervous systems or brain, no heart, and, with the exception of the box jelly, no eyes. They don’t even have bones or blood or dense muscles.

Corporal Structure Symmetry There are many different types of inverbretes and among them the three types of symmetry (bilateral, radial and asymmetrical) can all be found For example sponges are asymmetrical, Starfish and jellyfish have radial symmetry and grasshoppers and spiders have bilateral symmetry.

Corporal Structure All invertebrates are classified as being eukaryotes and are all multicellular jellyfish. Almost all invertebrates have tissues except for a select few such as sponges All invertebrates lack a cell wall

Corporal Structure Most invertebrates have organs and the higher invertebrates also have systems For example grasshoppers have organs such as eyes the heart and the reproductive organs. They have systems such as nervous, digestive and circulation

Reproduction and Lifecycle Reproduction in invertebrates can be sexual, asexual or hermaphroditic. For example spiders reproduce sexually. It is every males spiders goal to get as many females as possible pregnant. First the male spider has to locate a female. Next the spider has to beat off any other contenders to the female spider. Next comes courtship, the male spider has to signal he’ s the right species and not food. They usually express court ship through web building. If the female accepts they reproduce if she doesn't its all over

Reproduction and lifecycle Once a spider's eggs are fertilized, they have to stay safe from predators until the spiderlings can hatch out Some spider species will encase their eggs in a silken pouch and abandon them, and others will stay with them until the babies hatch.

Reproduction and lifecycle The spiderlings continue molting, growing larger until they reach sexual maturity. Then the entire cycle begins again -- males seek out females, and females lay eggs. Most spiders have a fairly short lifespan, ranging from a few months to a couple of years. But some spiders, such as various female tarantulas, can live as long as 20 years.

Respiration All invertebrates need oxygen to survive, meaning they do anaerobic respiration. For Example grasshoppers have small openings called spiracles, on the side there abdomens. These lead to a system of branched air tubes and tracheae, spreading throughout the body to all the cells. Air is pumped in and out of the tracheae by the muscular contractions and expansions of the abdomen. In this way O2 is brought in and CO2 is expelled

Digestion The many species of invertebrates use either a tubular, channel- network or saccular digestive system to digest food. A channel-network is several water channels lined with whip like structures called flagella that create a steady flow of water currents which bring nutrients in the water to the animal. For example sponges.

Digestion A tubular digestive system is with a complete tubular tract with an opening at each end ; one end is the mouth and the other is the anus. For example grasshoppers A saccular digestive system has a sac-like body composed of an outer and inner layer of cells and a central cavity. The outer layer is for sensory and protective covering, the inner layer of cells absorbs nutrients and the central cavity, possesses an opening that functions as both a mouth and an anus.

Circulation Many invertebrates do not have a circulatory system at all. Their cells are close enough to their environment for oxygen, other gases, nutrients, and waste products to simply diffuse out of and into their cells.For example flatwormsexchange gases exclusively by diffusion through their body surface. In some higher invertebrates, there are two primary types of circulatory systems -- open and closed.

Circulation Arthropods and mollusks for example have an open circulatory system. In this type of system, there is neither a true heart or capillaries as are found in humans. Instead of a heart there are blood vessels that act as pumps to force the blood along. The closed circulatory system of a few mollusks and other invertebrates( for example earthworms) is a much more efficient system. Here blood is pumped through a closed system of arteries, veins, and capillaries, much like us humans

Interesting Facts Invertebrates were the first animals to evolve. Invertebrates account for 97 percent of all known species. Invertebrates will eat almost anything that was or is alive. Many of the world's parasites are invertebrates.