Do annelids have an endoskeleton? do nematodes have an exoskeleton.
Annelids are segmented worms such as earthworms and leeches. Annelids have a coelom, closed circulatory system, excretory system, and complete digestive system.
The internal organs of annelids are well developed. They include a closed, segmentally-arranged circulatory system. The digestive system is a complete tube with mouth and anus. Gases are exchanged through the skin, or sometimes through specialized gills or modified parapodia.
Earthworms and other segmented worms have bodies made of many sections Page 2 called segments. Annelids also have a digestive system that has two openings. They also have a closed circulatory system.
The gizzard uses stones that the earthworm eats to grind the food completely. The food moves into the intestines as gland cells in the intestine release fluids to aid in the digestive process. The intestinal wall contains blood vessels where the digested food is absorbed and transported to the rest of the body.
The digestive system is complete, with a mouth and anus. The mouth in these organisms is terminal and is surrounded by lips bearing sense organ. Amphids and papillae are the main sensory organs. The nervous system consists of a nerve-ring that encircles the oesophagus.
Clams (and all mollusks) have a complete digestive system. It consists of a mouth where food is ingested, a short connecting tube called the esophogus, a stomach which temporarily holds food, and an intestine where food digestion and absorption takes place. … Food is distributed to the cells of the body by blood.
While segmented worms such as the earthworm and flatworms such as the planarian are both worms they differ in their means of moving from place to place and in their digestive system type. Earthworms have a complete digestive system, one which has two openings, the mouth and the anus.
Encyclopædia Britannica, Inc. Leeches breathe through the skin. The digestive system contains a crop, or pouch, in which food can be stored for several months. One to four pairs of eyes are located at the anterior end.
Annelids are found worldwide in all types of habitats, especially oceanic waters, fresh waters, and damp soils. Most polychaetes live in the ocean, where they either float, burrow, wander on the bottom, or live in tubes they construct; their colours range from brilliant to dull, and some species can produce light.
Cnidarians have an incomplete digestive system with only one opening; the gastrovascular cavity serves as both a mouth and an anus.
Until 2008 the earliest fossils widely accepted as annelids were the polychaetes Canadia and Burgessochaeta, both from Canada’s Burgess Shale, formed about 505 million years ago in the early Cambrian.
Leeches. Most leeches (annelid class Hirudinea) are bloodsucking parasites that attach themselves to vertebrate hosts, bite through the skin, and suck out a quantity of blood.
An earthworm has five hearts that are segmented and pump blood throughout its body,” said Orsmond. She said their structure was provided by a “hydrostatic skeleton” coelomic fluid (fluid within the body cavity) held under pressure and surrounded by muscles. “There are over 5 500 named species of earthworms worldwide.
So, the answer to your question is that all segmented worms have blood, while roundworms and flatworms do not. The blood colour depends on the molecule that carries oxygen in that worm. And most worms have red blood, just like us!
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.