- Annelid Worms - Insects Notes: Invertebrates - Annelid Worms - Insects

Invertebrates Animals that lack a backbone We are going to focus on the Annelids and Insects (a class of Arthropods)

Annelids Segmented Worms – each segment is a septa, have head & body segments Closed Circulatory System: Blood moves through vessels Consists of Earthworms (oligochaeta), Leeches (hirudinea) and marine worms (polychaeta)

Annelids

Annelid Transport Annelids have a closed circulatory system – blood moves through vessels. Blood is pumped to head & body transporting oxygen and carbon dioxide Have “hearts” that pump blood, really enlarged, muscular blood vessels

Annelid Excretion Annelids have a complete digestive system (contains both a mouth and anus) Food is absorbed in the intestine. Nearly every segment in Annelids has 2 nephridia that collect waste and transports it out of the body

Annelid Regulation Annelids have a nervous system that consists of nerve fibers in each segment connected by ventral nerve cords to a simple brain near the mouth Nervous system is used to sense the environment. Some Annelids have eyes.

Annelid Respiration & Nutrition Respiration – Annelids exchange gases through their skin. This is why their skin is moist and they live in moist environments Nutrition – Variety of feeding methods. (predators, filter feeders, decomposers) Food passes through digestive system where nutrients are absorbed.

Annelid Reproduction and Growth Earthworms & Leeches are hermaphrodites (don’t self fertilize) When 2 mate they exchange sperm. Each forms a capsule for sperm & egg which they leave behind. Marine Annelids have separate sexes and release sperm & egg into water for fertilization