What is the meaning of platyhelminthes?
What is the meaning of platyhelminthes?
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, platy, meaning “flat” and ἕλμινς (root: ἑλμινθ-), helminth-, meaning “worm”) are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates.
What type of nervous system do planarians have?
bilateral nervous system …a free-living flatworm such as Planaria consists of a brain, longitudinal nerve cords, and peripheral nerve plexuses (interlacing networks of peripheral nerves; from Latin plectere, “to braid”).
What type of nervous system do chordates have?
Dorsal nerve cord is another feature the chordates share. This is a hollow nerve cord that is towards the back compared to the notochord. In animals that have a backbone (vertebrates) this dorsal nerve cord becomes the brain and spinal cord. In other groups, it forms a simple nervous system.
Why are humans chordates?
Explanation: There is a long list of characteristics that organisms in Chordata phylum have, but the most important is the notochord. A notochord is flexible rod that runs along the back (dorsal) side of an animal. For humans is our notochord develops into the spinal cord, making us a chordate.
What type of nervous system do echinoderms have?
The adult echinoderm nervous system is composed of a central nervous system made up of a nerve ring connected to a series of radial nerve cords.
What are two important characteristics of echinoderms?
Characteristics of Echinodermata
- They have a star-like appearance and are spherical or elongated.
- They are exclusively marine animals.
- The organisms are spiny-skinned.
- They exhibit organ level of organization.
- They are triploblastic and have a coelomic cavity.
- The skeleton is made up of calcium carbonate.
Do echinoderms have a brain a nervous system?
Echinoderms such as starfish (more accurately referred to as sea stars), brittle stars, sea urchins and sea cucumbers do not have a brain or a brain-like organ in their bodies. The coordination of the nervous system is carried out by the nerves that radiate out from around the mouth and down into each arm or tentacle.
What is the function of the Madreporite?
The madreporite /ˌmædrɪˈpɔːraɪt/ is a light colored calcareous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve.
What does Madreporite mean?
: a perforated or porous body that is situated at the distal end of the stone canal in echinoderms.
What is the function of a starfish’s spines?
Spines: The sea star’s surface has many white spines that give the sea star a rough feel, and are used for protection.
What is the significance of Madreporite in starfish?
The madreporite is an essential part of the circulation system in echinoderms. Through this plate, which is also called a sieve plate, the echinoderm draws in seawater and expels water to fuel its vascular system. The madreporite functions like a trap door through which water can move in and out in a controlled manner.
What are the two surfaces of a sea star body?
The spiny upper surface covering the species is called the aboral or dorsal surface. On the aboral surface there is a structure called the madreporite, which acts as a water filter and supplies the sea star’s water vascular system with water to move.
What is the function of the pyloric caeca in a starfish?
The job of the pyloric caeca is to secrete enzymes that break down food to be used as energy. The sea star must excrete waste, which travels down an intestine that leads to the anus, which protrudes from the center of the disc on the oral surface of the sea star.
Did you know facts about starfish?
7 Amazing Starfish Facts
- Starfish can regenerate their own arms.
- They have no brain or blood!
- They wear tough, leathery skin.
- Starfish have eyes.
- Starfish move with hundreds of feet.
- Starfish can eat outside their body.
- Not all starfish are star shaped.