Two different kinds of nephridia occur within the Bilateria, protonephridia closed up by a terminal cell and metanephridia opening into the coelomic cavity. Both initially filter and subsequently modify intercellular fluids.
Q. Do Planaria have flame cells?
Flame cells are found in flatworms, including parasitic tapeworms and free-living planaria. They also maintain the organism’s osmotic balance.
Q. What are flame bulbs biology?
…the hollow cell, called a flame bulb (or flame cell) if it possesses cilia, or a solenocyte if it has a flagellum. In either form, the cilia or the flagellum wave filtered urine down the tube to the outside. They also have a system of tubules opening at the surface and ending internally in flame cells embedded…
Q. What is the structure of Protonephridia?
The Asplanchna protonephridial system, a primitive excretory organ concerned with water and salt balance, consists of 3–4 multinucleate cells with diverse structural and functional characteristics. The cells form a system of tubules lying in the pseudocoel cavity, one of which bears numerous ciliated flame bulbs.
Q. Is amphioxus a flatworm?
Explanation: Protonephridia or flame cells are the excretory structures in Platyhelminthes (Flatworms, e.g., Planaria), rotifers, some annelids and the cephalochordate Amphioxus. Protonephridia are primarily concerned with ionic and fluid volume regulation, i.e., osmoregulation.
Q. Do amphioxus have flame cells?
Amphioxus (a cephalochordate) has flame cells as excretory structures. These are specialized cells of excretory system that have pores through which filtrate is excreted and clusters of cilia that look like a flame under a microscope.
Q. What class is amphioxus?
In Asia, lancelets are harvested commercially as food for humans and domesticated animals. In Japan, amphioxus (B….
| Lancelet | |
|---|---|
| Phylum: | Chordata |
| Subphylum: | Cephalochordata |
| Class: | Leptocardii Müller, 1845 |
| Order: | Amphioxiformes Anonymous, 1886 |
Q. Why is amphioxus not a vertebrate?
Amphioxus also known as lancelet is a fish-like marine chordate. Unlike vertebrates, the dorsal nerve cord is not protected by bone but by a simpler notochord made up of a cylinder of cells that are closely packed to form a toughened rod.
Q. Why is amphioxus called Lancelet?
Lancelets are also called amphioxus, which translates to “both ends pointed,” because of the shape of their elongated bodies, as shown in Figure below. Although lancelets have a brain-like swell at the end of the notochord in the head region, it is not very highly developed.
Q. Is Branchiostoma a Urochordata?
(A) In Urochordata, the notochord is present only in the larval tail. (B) In Cephalochordata, notochord extends from head to tail region. (C) Branchiostoma belongs to Hemichordata. (D) Only one class of living members, class Cyclostomata represents the superclass Agnatha.
Q. Is notochord present in Urochordata?
Urochordates, like Herdmania have notochord and nerve cord present only in nerve stages. Notochord is present only in tail. Tadpole undergoes retrogressive metamorphosis and notochord and nerve cord is absent in adults, which is lost during metamorphosis. Hence, option C is correct.
Q. Why is it called Cephalochordata?
The lancelets are also called cephalochordates (Greek: kephale, “head”) because the notochord extends from near the tip of the tail to well into the anterior of the body. The segments of vertebrates and cephalochordates are so similar that they were almost certainly present in the common ancestor of the two groups.
Q. Do Lancelets have brains?
Lancelets (also called amphioxi) don’t have a brain quite in the same way we do, but they do have nerves running through the notochord that bunch up in a small, brain-like structure. Like other vertebrates, our brain tends to be divided into three major regions; the forebrain, midbrain, and hindbrain.
