What Does Segmentation Allow An Animal To Do With A Minimum Of New Genetic Material

Consignment 7: (continued)

Activities:
ACTIVITY i. DIVERSITY OF INVERTEBRATE ANIMALS
	Introduction to invertebrate animals
	The complication of invertebrate classification
	Terminology and major characteristics for invertebrate classification
	Identifying invertebrate animals by phylum
ACTIVITY two. RELATIONSHIPS Amidst VERTEBRATE Beast GROUPS
	Introduction to the kickoff land vertebrates
	Characteristics of the four groups of terrestrial vertebrates
	Are birds reptiles?

Segmentation, limbs, and skeletons
Note that the earthworm body was composed of nearly identical segments. Every bit with almost whatever trend, the origin of segmentation in the fauna kingdom is debatable. Virtually biologists agree that segmentation allows animals to become larger past repeated replication of the same structures. Sectionalisation besides allows for more precise localized motility. The pressure differences that are caused in the coelom past contraction of muscles in one segment can be isolated from other segments.

Once a number of segments were present, different segments could become specialized for different functions. The about interesting case of segment specialization involves certain sessile, bottom-habitation, marine annelids. Segments develop at sure times of the year that bear reproductive structures. These structures are modified parapodia, segmental appendages that are also used for swimming. Some of these reproductive segments can split and come to the surface in swarms to mate.

Note that in the Arthropoda, the phylum containing the greatest number of subgroups, many species have segments that are not involved in locomotion.  Some segments may course part of a well-divers head, where as others segments course an abdomen that houses reproductive structures and other organs.

Phylum Arthropoda Note the segmental torso program with three specialized regions in this insect, a member of Phylum Arthropoda.

Locomotory appendages, or limbs, allow a great deal of movement from a minimum amount of muscular contraction. The bulk and weight of the body moves in the forward management while just the limbs are moved back and along. Lengthening limbs (given a rigid skeleton) magnifies the distance that the operating muscles contract, increasing the speed of the animate being even though muscular wrinkle is comparatively slow. Jointed limbs provide a system of levers that permit precise placement of antagonistic muscles, allowing cracking flexibility of motion.

View video of a crab waking sideways

Molluscs (Phylum Mollusca) accept no obvious segmentation and no limbs, simply many of them do have a hard shell that serves as protection for their soft bodies. Most molluscs, including those that live on country, have a large muscular mass called a "foot" which allows them to move. In ii familiar molluscs, the snail and slug, the human foot is very big and comprises the ventral side of the torso. Rippling waves that pass through this muscular foot permit the brute to motion forward slowly (sluggishly or at a snail's pace!). The snails and slugs can also be identified by the eye stalks protruding from their heads and, in the case of snails, by a coiled shell. Note that slugs lack a shell, although they are close relatives of snails; both are in the gastropod group.

View this video of snail locomotion: the video first shows how a snail glides over a rock, and then switches to a snail attached to the inner wall of an aquarium. Annotation the ripples passing over the underside of this snail'southward foot.

Rigid skeletons appeared in the fossil record at the onset of the Cambrian menstruum, roughly 600 million years ago. In that location are 2 full general types: an exoskeleton (external) and an endoskeleton (internal). Exoskeletons accept an advantage in strength to weight ratio. This means that for a given quantity of skeletal material, a thin tubular exoskeleton is far stronger than a solid, rod-like endoskeleton. This explains the evolutionary advantage of pocket-sized animals like insects. Exoskeletons also support and protect soft internal organs and add a protective coating that prevents desiccation. However, animals with an exoskeleton cannot grow larger unless they molt (shed the exoskeleton and abound a new, larger one). Very large animals with exoskeletons would demand larger muscles that are bulkier and harder to construct (if limbs are to remain flexible at joints). Four-foot dragonflies and eight-foot scorpions did be on this planet in the past, and probably were the biggest and "badest" creatures of their times. The lack of modernistic forms of this size with probably tin can be explained by 2 factors. There is less oxygen available in the atmosphere in the current age, and large-exoskeleton forms would confront vehement competition from the agile organisms with endoskeletons that now be.

Observe the system of skeletal and muscular structures in the human being arm and crayfish forelimb. The man (like all vertebrate animals) has an endoskeleton, whereas the crayfish (like all arthropods) has an exoskeleton.

Symmetry and cephalization
Adult trunk symmetry is correlated with lifestyle. If the adult is sessile, radial symmetry is ordinarily the rule. Almost self-mobile animals are bilaterally symmetrical with the end that enters a new surroundings get-go housing the "brain" and well-developed sensory structures. This anterior cease is known every bit a head. Exceptions to the dominion are the members of Phylum Echinodermata which have a peculiar, v-fold symmetry. Echinoderms also have "invented" a unique way of moving, tube feet. The sea star is a expert example. This echinoderm has 5 long, flexible arms by which it tin correct itself, if turned upside downwardly. Withal, locomotion is performed by a huge number of tiny "tube feet" that extend from the underside of each arm. Notice these motions in the following video.

View video of body of water star locomotion

Identifying invertebrate animals by phylum

You now take sufficient data to identify the phylum to which an invertebrate beast belongs. Yous must examine 7 animals shown in the videos beneath and make up one's mind which Phylum it belongs to. Your choices are Cnidaria, Platyhelminthes, Annelida, Nematoda, Arthropoda, Mollusca, and Echinodermata. To assist you, and and then that y'all tin practice using a key, a simple central to invertebrates is provided. Apply it as you study the videos, if yous need assistance.

View each video below and determine the Phylum to which each animal belongs. And then reply question 2 on your work canvas.

Video of Animal 1

Video of Animal 2

Video of Animal 3

Video of Animal iv

Video of Brute 5

Video of Animal 6

Video of Animal seven

Source: https://webprojects.oit.ncsu.edu/project/bio181de/Lab/animal_diversity/animal_diversity2.html

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