Post on 20-Aug-2015
The General Body Plans of Animals
Prepared by:Group 1 Morning
Joseph Martin PaetGladys Kim Remolacio
Jesebel GarlanRuby Cocal
Jeremy Nacido
INTRODUCTION Most animals are bilaterally symmetric, including humans.It could be divided into matching halves by drawing a line down the center.It permits streamlining, favors the formation of a central nerve center, contributes to cephalization, and promotes actively moving organisms.
Radially symmetric animals are symmetrical about an axis extending from the center of the oral surface.
Radial Symmetry
Coral
Jelly Fish
REGIONS Segmentation the division of some animal body plans into a series of repetitive sections. “Advanced” animals have body segments, and specialization of tissue.
Metamerism segments are similar with each other.Tagmatization segments are different and may become fused to fused to a functional groups/tagmata.
Terms to be Familiar With
Anterior head-end
Posterior tail-end
Cephalic toward the head
Caudal toward the tail
Dorsal back side
Ventral belly side
Lateral on or toward the side
Medial on or toward the middle
Proximal toward the central part
Distal toward the extremities
Peripheral near the surface of the body
The RoundwormAscaris lumbricoides, a common intestinal roundworm having a bilateral symmetry. It lacks true segmentation and appendages. It is covered with a tough, elastic cuticle, bearing minute striations. Four whitish longitudinal lines extended along the body, one dorsal, one ventral, and two lateral. The mouth opens at the anterior end between three rounded lips. The anus is a transverse slit close to the posterior end of the ventral surface.
Figure 7.2
The Earthworm The Pheretima has a bilaterally symmetrical body, long and cylindrical, bluntly tapered at each end, and somewhat depressed posteriorly. The body is organized in a linear series of similar segments (somites/metameres) which is called mesmerism. The mouth is in the first somite and the vertically oval anus, in the last somite. The clitelium is a conspicuous glandular swelling over the somites 32 to 37. Setae – minute, rod-like chitinous appendages.
Clitelium
Mouth
Anus
Somites
Figure 7.3
It is divided into three segments.
The segments are not similar and is referred to as tagmata.
The Cockroach
2. The Thorax
The prothoracic plate is a broad plate located anteriorly.
Prothoracic plate
Figure 7.6
Forewing spread in the mesothorasic area while the hind wing is on the metathorasic area. The hindwing is the one used in flight.
2. The Thorax
Forewing/Elytrom
Hindwing
Figure 7.6
Cercus
Answers to Self Assessment Question
SpeciesSegment
s present
Number of Legs &
segments attached
Appendages present
Sensory Organs present
and segments
where attached
Cockroach 6 legs; 11 seg.
Head, Thorax, Abdomen
Antennae, Cerci, eyes
Shrimp 6 w. legs; 11 seg
Cephalothorax, Abdomen, tail
Antennae, eyes
Crab 6 legs; 8 seg. Abdomen, head
Antennules, eyes
Spider 8 legs: 9 seg. Cephalothorax, abdomen
Ear, hair, eyes
1. Compare and contrast the following invertebrates based on the following:
Species Locomotory Organs Habitat Body
CoveringBody
Regions
Fish Tail and fins Water Scales Head, trunk, tail
Toad Legs Both land and water Scales Head, trunk
Cow Legs Land Fur Head, trunk
Birds Wings and legs Land Feathers Head, trunk,
tail
Snake Tail, body Land and water Scales Head, tail
2. Compare and contrast the tod with fish, other amphibians, reptiles, birds, and mammals based on the following:
What is the adaptive significance of segmentation in animals?
Segmentation is the division of an animal into similar parts. It's main significance is that it provides a simple way of making a small animal into a larger one - basically by duplicating a segment two or more times an animal can be made bigger without complex alterations. This has particular significance in evolution where it is generally believed that larger animals evolved through a simple genetic mutation which generated multi-segmented forms from non-segmented forms.Segmentation is visible to one extent or another in virtually all larger fauna - from insects and earthworms to vertebrates (the spinal column is an example of segmentation - the repeated use of vertebral disks to create a larger creature than would easily be possible by simple enlarging one vertebra)