: a tendency in the evolution of organisms to concentrate the sensory and neural organs in an anterior head.
What is cephalization and why is it important?
Cephalization is the formation of a central nervous system in organisms. … Cephalization is important in that it allows for the organism to make quick movements. It also allows for the organism to have an axis of symmetry, further making quick movements possible as the organism can either find prey or avoid being prey.
What does the term cephalization mean quizlet?
Cephalization. means having “head” sense organs and nerves are in front of body. Sponges are sessile, but they have flagella.
Which of the following is an incorrect association of an animal germ layer with the tissues or organs to which it gives rise?
a sessile existence. Which of the following is an incorrect association of an animal germ layer with the tissues or organs to which it gives rise? sponge.
What Phylums have cephalization?
Members of the Phylum Platyhelminthes (particularly planarians, Class Turbellaria) have brain and sense organs in front of the animal. This is known as cephalization. The sense organs are the first to make contact with the environment in cephalized animals.
What does it mean to call something cephalized?
The definition of cephalization means the trend in evolution for the nervous system and the sensory organs to be positioned near the human or animal head. An example of cephalization is the tendency for an animal’s ears to be on its head. noun.
Are all worms cephalized?
Though not obvious, cephalization does exist in an earthworm. … Hence, the earthworm exhibits cephalization.
What is the group that comprises all animals called?
The animal kingdom is divided into Parazoa (sponges) and Eumetazoa (all other animals). As very simple animals, the organisms in group Parazoa (“beside animal”) do not contain true specialized tissues.
Are humans cephalized?
Examples of Cephalization
Three groups of animals display a high degree of cephalization: vertebrates, arthropods, and cephalopod mollusks. Examples of vertebrates include humans, snakes, and birds. … Animals from these three groups exhibit bilateral symmetry, forward movement, and well-developed brains.
Are all animals cephalized?
All vertebrate animals qualify as highly cephalized organisms on account of their distinct heads, well-developed brains, elaborate nervous systems and complex thought processes.
Is cephalized a word?
from The Century Dictionary.
Exhibiting cephalization; having the head and anterior members of the body well developed or well distinguished.
What is Cephalisation Class 11?
Cephalisation involves the * concentration of nervous tissue (brain) and sense organs in the head. This arrangement is an asset in an adjustment with the environment, as the anterior end of a moving animal is the first to encounter changes in the area it is entering.
What is radial symmetry in zoology?
Radial symmetry is the arrangement of body parts around a central axis, like rays on a sun or pieces in a pie. Radially symmetrical animals have top and bottom surfaces, but no left and right sides, or front and back. … Radial symmetry: Some organisms, like sea anemones (phylum Cnidaria), have radial symmetry.
Are sponges cephalized?
Sponges have no particular symmetry; they are not radially or bilaterally symmetrical. Cephalization means having a head. … Cephalization only occurs in bilaterally symmetrical animals.
What is a scolex Why is it needed?
The head, or scolex, bears suckers and often hooks, which are used for attachment to the host. The body covering is a tough cuticle, through which food is absorbed.
What is the name of the body cavity in the earthworm?
Body segments
The body cavity (coelom) between the muscular body wall and intestine is divided into segments, with a membrane (septum) between each.
What are the 3 types of worms?
Worms are classified into three major phyla, or groups. They are flatworms, roundworms, and segmented worms.
What is meant by the term sessile?
1 : attached directly by the base : not raised upon a stalk or peduncle a sessile leaf sessile bubbles. 2 : permanently attached or established : not free to move about sessile sponges and coral polyps.
Are flatworms cephalized?
Flatworms have a cephalized nervous system that consists of head ganglion, usually attached to longitudinal nerve cords that are interconnected across the body by transverse branches.
Are cnidarians cephalized?
Cnidarians are radially symmetrical (i.e., similar parts are arranged symmetrically around a central axis). They lack cephalization (concentration of sensory organs in a head), their bodies have two cell layers rather than the three of so-called higher animals, and the saclike coelenteron has one opening (the mouth).
In which phylum would you find flatworms such as flukes tapeworms and Planaria?
The Phylum Platyhelminthes (flatworms) includes planarians (Class Turbellaria), tapeworms (Class Cestoda), and flukes (Class Trematoda). The planarians are harmless, free-living flatworms. They live in an aquatic environment (freshwater or marine) or on moist soil.
Are porifera deuterostomes?
Porifera, the sponges, and cnidaria, the jellies and kin, are actually neither. Determining Protostome or deuterostome for phyla? They are diploblastic animals with two layers, the outer dermal layer and the inner gastral layer.
What group of animals are known to have a true notochord?
The phylum Chordata contains two groups of invertebrate chordates, but the most conspicuous and familiar members of Chordata are the vertebrates. Phylum chordata: All chordates are deuterostomes, possessing a notochord.