How do land dwelling annelids breathe

The digestive system is one-way, end to end, and is the most complex one we've seen so far, with sections that have unique structures and purposes:.

Blood is actively moved through a closed circulatory system by muscles that go around the vessels in the front part of the worm. The blood vessels and digestive tract go through the septa like straws through the lid of a cup. Wastes are filtered out of the blood and go out through pores in the surface of the worm. Annelids have special organs called nephridia to filter wastes from the blood for excretion.

The land-dwelling annelids, like earthworms, breathe differently than freshwater and marine annelids. Water-dwelling annelids such as leeches have gills for getting oxygen from the water. The surface of a land-dwelling earthworm is covered with blood vessels that exchange gases with the air via water. This is why earthworms die when stranded on the sidewalk. They dry out and can't breathe.

Annelids can change the shape of each section separately, which helps them move. One section squeezes and then the next to wriggle the worm along. Annelid muscles work against the fluid-filled hydrostatic skeleton. Annelids often have some sort of bristles on the outside of their body called setae , which help them move. Some annelids also have parapodia "beside feet" or "almost feet". These are little parts that stick out from each section and act a bit like feet.

All annelids reproduce sexually, but some have separate sexes while others are hermaphrodites. They also all lay eggs. Life cycles are different, though, between land and marine annelids. Different adaptations are needed on land than in water and we can see this within a phylum as well as between phyla.

Marine annelids go through two different stages in life: for example, a trochophore floats through the water and then changes into the adult form by adding segments.

Land annelids produce young that are little versions of adults. Some annelids can also reproduce asexually. In some annelid species, a new animal may bud from a parent or one animal can split into two.

Some annelids can also regenerate parts if a segment is broken off. Yes, it's true that earthworms can regenerate, but only from the front half. Think leeches are disgusting? Well, you're right. But they must be pretty smart, because a leech has 32 brains. Leeches are made up of 32 segments, and each segment gets its very own brain.

Cleaning out the blood : Worms don't have kidneys, but they have something serving the same purpose. Worms have nephridia to filter out the dead cells and other wastes that are sloughed into the blood.

Wastes from the nephridia are eliminated through the same opening as the digestive wastes. Worm urine is more dilute than ours, but has ammonia as well as urea. Heartbeats : Worms don't have just one heart.

They have FIVE! But their hearts and circulatory system aren't as complicated as ours -- maybe because their blood doesn't have to go to so many body parts. Moving around: Worms have two kinds of muscles beneath their skin.

The outer layer of muscles are circular muscles, which decrease the diameter but stretch the length of the earthworm's body when contracted. The inner layer of muscles are longitudinal, which shorten but widen the body when contracted. Every segment of a worm's body except the first and last has four pairs of tiny, stiff hair-like projections called setae. To move forward, this is what a worm does: First it grips the soil with some of its back setae so its back part can't move.

Then it squeezes its circular muscles, which makes its body get longer. Since the back of the body is gripping the soil, the front part of the body moves forward. Then the front setae grip the soil and the back setae let go. Then the worm squeezes its longitudinal muscles, which makes its body shorter. The back part moves forward. Try This! Activities Journaling Project Imagine you are the first worm on earth with the ability to write in a diary.

Based on your understanding of how worms live, write some diary entries. Try to pick days when you won't get gobbled up by a robin! Choose three days from the following: a nice, sunny day after an overnight rainstorm in spring a day when it's pouring rain in spring a cool, moist summer day a hot, dry day in the middle of summer a warm, misty day in autumn a cold, windy day in autumn Valentines. Imagine you're a worm. Use art materials to create a Valentine for your best friend. Heart Sounds.

Imagine what a worm's five hearts would sound like if you were listening through a stethoscope. Practice making the sounds you think you would hear. Use your mouth or any objects to create the heart sounds. Take turns with your friends to hear each other's versions of worm heart sounds.