Animal Kingdom Test - 7

Tunicin is also called as animal cellulose. It is a substance present in the mantle, or tunic of the tunicates, which resembles or is identical with the cellulose of the plant kingdom. these are structural cellulose which is mainly present in the shell of several animals like tunicates.

Metamorphosis is the phenomena in which there are changes which transform the organism from its juvenile stage to adult stage. In the case of retrogressive metamorphosis, the larva possesses the advanced features which get lost during the development. The adult is sedentary or degenerated with the primitive characters. Retrogressive metamorphosis is a characteristic of ascidians. They are from the group of Urochordates or Tunicates. The active and alert larva metamorphoses into a retrograde and sedentary bag-like creature. The adult remains attached to a rocky substratum. 
Thus, the correct answer is option B.

Pronephros is the most basic of the three excretory organs that develop in vertebrates, corresponding to the first stage of kidney development. It is succeeded by the mesonephros, which in fish and amphibians remains as the adult kidney.The excretory organs of Amphioxus occur as segmentally arranged structures throughout the pharyngeal region and may be divided into three components: the solenocytes, the renal tubule, and the renal glomerulus.The solenocytes possess foot processes that rest upon the coelomic surface of the ligamentum denticulatum.

The dorsal hollow nerve cord is part of the chordate central nervous system. In vertebrate fishes, the pharyngeal slits become the gills. Humans are not chordates because humans do not have a tail. Vertebrates do not have a notochord at any point in their development; instead, they have a vertebral column.

Amphioxi are small marine animals found widely in the coastal waters of the warmer parts of the world and less commonly in temperate waters. Both morphological and molecular evidence show them to be close relatives of the vertebrates. A brief treatment of amphioxi follows. For full treatment, see cephalochordate.

Herdmania is called as degenerated Chordata because its excretory system contains protonephridia. The absence of heart and kidney, paired limbs or paired fins, a distinct head, distinct paired sense organs, gonads are without gonoducts.
So, the correct answer is option D.

A neural gland (supra neural gland) is present in the brain in Herdmania. It is brown in colour. It is present in the mantle. It is 4 mm in diameter. It shows branching tubules. So, the correct answer is option B.

The fertilized eggs of urochordates undergo holoblastic and unequal cleavage. The egg develops to form the blastula. The blastula shows upper micromeres and lower macromeres. When the invagination of the macromeres occurs, gastrulation takes place and the structure of gastrula is formed. This gastrula develops into a tailed larva. This larvae is called as tadpole larva.The larva is free-swimming and exhibits all chordate characteristics. It has a notochord, a dorsal nerve cord, pharyngeal slits and a post-anal tail.
Thus, the correct answer is option B.

Chordates are animals possessing a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle and a post-anal tail for at least some period of their life cycles. So, the nerve cord is hollow and is placed dorsal to the gut.
So, the correct answer is option B.

Chordates are animals possessing a notochord. The notochord, later on, gives rise to a bony vertebral column, which surrounds and protects the spinal cord.
So, the correct answer is option D.

Retrogressive metamorphosis means degenerative changes wherein an active larva metamorphoses into a sedentary adult. In Urochordata or tunicates, the notochord is present only in the larval tail. Tail and nervous system are reduced in adult because the adult is sedentary. Common examples of Urochordata are Ascidia, Salpa, Doliolum. Salpa is a barrel-shaped, planktonic tunicate. Doliolum is a genus of tunicates.
Thus, the correct answer is option C.

Chordates have central dorsal hollow nerve cord, which is absent in non-chordates. Chordates possess a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail for at least some period of their life cycles.
So, the correct answer is option B.

The solitary ascidian Herdmania momus is one of the most commonly encountered species of ascidians. While commonly referred to simply as sea squirts, this name is ambiguous, as it can refer to any member of the sub-phylum Tunicata.This solitary ascidian is sometimes referred to as the red-throated ascidian, as its two siphons are a vivid red in colour. However, most solitary ascidians that are encountered are so covered in algae that the coloration is often not visible. When found at depth the red colourations may also not be visible, as lower frequencies of light are absorbed by the layers of water above.

The solitary ascidian Herdmania momus is one of the most commonly encountered species of ascidians. While commonly referred to simply as sea squirts, this name is ambiguous, as it can refer to any member of the sub-phylum Tunicata.

In chordates, four common features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Protochordates are an informal category of animals (i.e., not a proper taxonomic group). This group has the animals that possess some but not all characteristics of chordates. They have pharyngeal gill slits and a dorsal nerve cord, however, they lack vertebral column and paired appendages.
So, the correct answer is option D.

Branchiostoma is one of the few living genera of lancelets. It is the type genus of family Branchiostomidae. These small vaguely eel- or snake-like animals are close relatives of vertebrates.

Adult tunicates, such as the ones shown in Figure below, do not bear much resemblance to other chordates. As adults, most tunicates are sessile (they do not move around) filter feeders that lack a notochord and a post-anal tail. They also lack the body segmentation that is found in other chordates characters.

Herdmania is a marine animal. They belongs to phylum Chordata. They are included in the sub phylum Urochordata. They are sedentary type of animals. They are fixed to the substratum or rock with the help of the flat base like structure. Whenever the organisms are disturbed, they suddenly contracts their body and emits inner contents with force through its apertures. So, they are commonly called as sea squirt. The larvae show retrogressive metamorphosis in which there is loss of advanced features while development to adult. 
Thus, the correct answer is option A.

Chordates are basically segmented (metameric) animals, although this repeating pattern often can be seen strongly only as embryos develop. One can see a hint of segmentation in the construction of the backbone, it's attached muscles, and our peripheral nervous systems. 

Therefore, the correct answer is option C.

The vertebral column is a series of approximately 33 bones called vertebrae, which are separated by intervertebral discs. The column can be divided into five different regions, with each region characterised by a different vertebral structure.

Cephalochordata are small, segmented marine animals that possess elongated bodies with a notochord that extends the length of the body, extending from head to tail, persisting throughout the animal's life. Cephalochordates are represented in modern oceans by the Amphioxiformes. 

Lateral line system, also called lateralis system, a system of tactile sense organs, unique to aquatic vertebrates from cyclostome fishes (lampreys and hagfish) to amphibians, that serves to detect movements and pressure changes in the surrounding water.

Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. These can be traced in cartilaginous fish, such as sharks and rays. Early embryos of different vertebrates resemble each other in possessing certain similar structures, like gill slits. Therefore gill slits of chordates occur in the pharynx of all chordates embryos and pharynx of some aquatic adult chordates. Hence, option C is correct.

 A method of feeding used by lancelets and many other aquatic invertebrates. The movement of cilia causes a current of water to be drawn towards and through the animal, and microorganisms in the water are filtered out by the cilia. "ciliary feeding.

Metamorphosis is the phenomena in which there are changes which transform the organism form its juvenile stage to adult stage. In the case of retrogressive metamorphosis, the larva possesses the advanced features which get lost during the development. The adult is sedentary or degenerated with the primitive characters. Retrogressive metamorphosis is a characteristic of ascidians (Urochordata or Tunicata). The progressive, active and alert larva metamorphoses into a retrograde and sedentary bag-like creatures. The adult remains attached to a rocky substratum all their lives and use a current of water passing through their large and perforated pharynx to collect microorganisms on which they feeds.
Thus, the correct answer is option B.

Cephalochordates are Urochordates are marine organisms. In the members of the cephalochordates, the notochord is persistent. The notochord is present throughout the body. In case of the members of the Urochordates, the notochord is present in posterior half of the body of the organism. Thus, the organisms in the two groups are divided on the basis of the length of notochord. 
Thus, the correct answer is option A.

Pyrosoma are tunicates. These are the free-floating colonial tunicates. These organisms live on the upper layers of the oceans. They are cylindrical or conical shaped colonies. The colonies are made up of many number of individuals which are called as zooids. They are brightly bioluminescent. They have the ability to flash a pale blue-green light. This light is bright enough to be seen from a very far distance.
Thus, the correct answer is option A.

Urochordata is also called as Tunicata or tunicates. The term tunicates has been derived from the unique outer covering or tunic. The tunic is formed from proteins and carbohydrates. The tunic acts as an exoskeleton. The tunic is also referred as test. 
Thus, the correct answer is option D.

The notochord is also known as chorda dorsalis. It is a rod-shaped cord of cells on the dorsal aspect of an embryo, defining the primitive axis of the body and serving as the center of development of the axial skeleton. It is the common factor of all chordates.
So, the correct answer is option A.

Balfour (1880) established the phylum Chordata which included the vertebrates, Amphioxus and tunicates.The Phylum Chordata unites the diverse forms having a notochord, hollow dorsal nerve cord and pharyngeal gill-slits.

Urochordata is also called as Tunicata or tunicates. The term tunicates has been derived from the unique outer covering or tunic. The tunic is formed from proteins and carbohydrates. The tunic acts as an exoskeleton. The tunic is also referred as test. All urochordates are marine organisms. Most of them are sedentary and some are pelagic. The body is covered by a test. It is formed by tunicine which is rallied to cellulose. 
Thus, the correct answer is option B.

Urochordate animals show all three characters, like neoteny, retrogressive metamorphosis and paedogenesis. Neoteny is the phenomenon whereby an organism retains larval characteristics, when sexually mature and most likely occurs by mutation, in the course of evolution. They only reproduce sexually and produce tadpole-like larvae that are free-swimming and metamorphose into the adult in the water column. The larvae possesses advanced features like the notocord. The features are lost while the development of the larvae to form an adult. This type of metamorphosis in which there is retrograde loss in the features of the larvae is called as retrogressive metamorphosis. Paedogenesis is the act of reproduction by an organism that has not achieved physical maturity. 
Thus, the correct answer is option D.

The Urochordata , also known as Tunicates and Ascidians , are more commonly known as "sea squirts." They belong to the same phylum as the vertebrates although adults do not have a backbone. The name sea squirt comes from the way water is pushed out through the exhalant siphon.

A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata, which is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords. The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals.Because of the high concentration of vanadium in the blood, it has been assumed that vanabins are used for oxygen transport like iron-based hemoglobin or copper-based hemocyanin. Unfortunately no scientific evidence can be found to back this hypothesis.

Protochordates are closely related to vertebrates. These lack some of the peculiar characteristics of chordates like the true skull, brain, skeleton. These are invertebrates. 
So, the correct answer is option A.

Hemichordata closely relates the Chordates. It contains marine deuterostome animals. They have a tubular structure known as stomochords. Stomochords arise in embryonic development as an out-pocketing from the roof of the embryonic gut anterior to the pharynx. In adults, they extend dorsally from the pharynx into the proboscis and serve to communicate with the oral cavity. Their walls are composed primarily of epithelial cells, but ciliated and glandular cells are also present.Balanoglossus belongs to the Hemichordata phylum. So, it has buccal diverticulum.
So, the correct answer is option C.

The wheel organ is found in amphioxus, which is a specialized epithelium in the roof and sides of the adult lancelet oral cavity. It borders the oral epithelium proper. The wheel organ cells are tall and strongly ciliated and have dark, heterochromatin-rich nuclei. It draws food through the use of its cilia for digestion. 
So, the correct answer is option B.

The epithelial lining of oral hood forms 6 to 8 pairs of finger -like folds each formed by a ciliated groove bounded by a ciliated ridge and collectively called as 'wheel organs' or 'Muller's organs'. In rotifers, the cilia of wheel organ set up a vortex so that food can sweep into the mouth from water current. Hence, option B is correct.

The unpaired 'Hatscheck's nephridium' is the largest and most anterior of the nephridia in the body of the Branchiostoma. It is a single tubule which lies on the left side of the notochord running parallel to the left anterior aorta. It stretches from the anterior vestibule to a point immediately posterior to the velum where it opens into the endodermal pharynx. 
So, the correct answer is option B.

Herdmania is commonly known as sea squirt. It is an exclusively marine organism. They are found in shallow water. These are solitary and sedentary organisms which are attached to a rocky sea bottom. They are imbedded in a sandy flour. It is a cilliatory feeder and a microphagus animal. It is hermaphrodite and fertilization is external and development is indirect. 
Thus, the correct answer is option B.

Amphioxus are fish-like marine chordates. The notochord is a flexible rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In case of Amphioxus, it is retained in the adults.
So, the correct answer is option C.

Protochordates are an informal category of animals. Protochordates are also known as Acrania. They are characterized by the absence of vertebral column. They do not have the skull or cranium. They do not possess jaws. This group is composed of the phylum Hemichordata and the subphyla Urochordata and Cephalochordata. 
Thus, the correct answer is option B.

Cephalochordates are the animals which belong to the chordates. The cephalochordates like Amphioxus and lancelets are known as filter feeders. These are the organisms that use cilia to generate a current of water. This current helps the movement of phytoplankton particles into the mouth. The fluid or water is entered through the ciliary current into the mouth of the organisms. 
Thus, the correct answer is option A.