ZOO301 Handouts by VUBuddy

HANDOUTS

ROTECTION, SUPPORT AND MOVEMENT 1.

Introduction to Protection, Support and Movement

Definition of Animal: A thing having all the properties of life i.e. Nutrition and digestion respiration, excretion, body fluid regulation, reproduction and development etc 2.

Evolutionary Concept:

Comparative perspective: It is based on the idea that a system cannot be fully understood without comparing it with the systems in different animals. 3.

Protection: Integumentary system

In Protozoa In Multicellular Invertebrates Animals In Vertebrates Support: Skeletal system

Movement: Non Muscular and Muscular System An Introduction to Animal Muscles

4.

Integumentary System of Invertebrates (Protozoa)

Integument is the external covering of the animal. It protects the animals from mechanical and chemical injury. It protects the animal from the invasion of microbes. It also regulates the body temperature and excretion of wastes. Also responsible for the conversion of sunlight into Vitamin D Plasma Membrane Pellicle Calcium Carbonate shell 5.

Integumentary System of Multicellular Invertebrates

Epidermis: single layer of columnar cells. Cuticle: may be thin or elastic as in rotifers or thick and rigid as in crustaceans and insects. Calcium Carbonate Shell: as in Cnidarians (corals) Tegument: a complex syncytiumfound in parasitic flukes and tapeworms. Exoskeleton: most complex integument found in Arthropods 6.

Integumentary system of vertebrates (Jawless fishes, Cartilaginous fishes)

Jawless fishes include Lamprays and Hagfishes. Of several types of epidermal glands, one secretes cuticle. In Hagfishes, slime is secreted by multicellular epidermal glands and covers the body surface. Skin of Cartilaginous fishes (sharks) is multilayered and contains mucous cells and sensory cells. Dermis contains small placoid scales in the form of denticles similar to vertebrate teeth. The denticles are protective in function. 7.

Integumentary system of bony fishes

Bony fishes (teleosts) contain dermal scales. The dermal tissue is covered over by epidermis. The scales grow at the margins and at the lower surface. Growth lines thus developed are useful to determine the age of the fish. The skin of the bony fishes is permeable to gases. The dermis is richly supplied with blood to facilitate in respiration. The epidermis also contains mucous glands. Mucus prevents the fish from infection. In some species the mucus contains poisonous alkaloids. Deep water fishes have rhodophores that help lures and warnings 8.

Skin of Amphibians, Skin of Reptiles

Amphibian skin has layers i) Epidermis ii) Dermis Epidermis is stratified. Dermis is thick containing, pigment layer, mucous & serous glands. During evolution keratin production increased in outer layers of the skin. Skin of Reptiles: i) Epidermis is thick, outer most layer is stratum corneum. Epidermis is modified into keratinized structures e.g. scales, scutes, rattles, claws plaques and spiny crests. These structures are protective in function. Skin of Reptiles: Molting or shedding of skin also occurs in reptiles e.g. snakes. The skin of reptiles reflects their greater commitment to a terrestrial existence. 9.

Skin of Birds

Skin of birds show many reptilian features with no epidermal glands except uropygial or preening gland. Epidermis is thin having two to three cell layers. Outer keratinized layer is quite soft. Feathers are the most prominent epidermal derivatives. The dermis of birds is similar to those of reptiles containing blood and lymphatic vessels, nerves and sensory bodies. Feathers are important in thermal regulation, flying and behavior. 10.

Skin of Mammals I

Notable features of mammalian skin are:

1. Epidermis
2. Epidermal glands.
3. Hair
4. Dermis

Rapid cell division occurs in the deeper parts of epidermis. As these cells come up the surface, where they die and become keratinized. Later these cells become the outer skin layer, and called the stratum corneum (SC). The SC is the first line of defense against toxins and microbes. Dermis is the thicker portion of mammalian skin. It contains blood vessels, lymphatic vessels, nerve endings, hair follicles, small muscles and glands. The Hypodermis lies underneath the dermis that consists of loose connective tissue, adipose tissue, and

Main Functions of Mammalian Skin: Main barrier of the body Regulates body temperature by sweating. On exposure to sunlight a chemical present in the skin is converted into Vitamin D. Skin is an important sense organ containing sensory receptors for heat, cold, pressure and pain.

Mammalian Skin Glands:

Sudoriferous glands (sweat glands) Sebaceous glands secrete sebum Sebum is a: i) Lubricant, ii) Skin-softening agent and iii) Also acts as a pheromone. Pigmentation of the skin: Chromatophores- Melanin in human skin. Other skin colors in various mammals help camouflaging, communication, reproductive status etc, Some colors is due to color of blood. Hair is composed of keratin-filled cells that develop from epidermis. Arrector pili muscles are attached to the connective tissue surrounding the hair follicle. On contraction of pili muscles the hair gets erect. This condition is called “Goose hump” in human. In other mammals this condition helps warm the animal in cold environment. Nail, is one of the characters of Pimates. like hair, nails are the modifications of epidermis. Other mammals have claws and hoofs. Horns are keratinized derivatives of mammalian skin. (Horns are not to be confused with the bony antlers).

Movement and Support: Skeletal system in invertebrates

Body size increased dramatically as organisms evolved from unicellular to multicellular animals. Systems involved in movement and support evolved simultaneously. With respect to support, organisms have three kind of skeletons:

1. Hydrostatic
2. Exoskeleton
3. Endoskeleton

Four cell types contribute to movement:

1. Amoeboid cells
2. Flagellated cells
3. Ciliated cells &
4. Muscle cells

Four cell types contribute to movement:

1. Amoeboid cells
2. Flagellated cells
3. Ciliated cells &
4. Muscle cells

Earthworm: Longitudinal and circular muscles contract alternately creating a rhythm that moves the earthworm. Hydro skeleton keeps the body from collapsing when the muscles contract.

Exoskeleton is a rigid external frame-work of the body. Functions: Provides site for muscle attachment. Supports and protects the body like a shield. Prevents internal soft tissues from drying out. Provides protection from enemies. Exoskeleton in Arthropods: Cuticle waterproofs the body. It limits the animal growth. Periodic shedding of exoskeleton. At the joint regions the cuticle is flexible, where the antagonistic muscles function. At wing joints, a protein, resilin, stores energy on compression and then releases energy to produce movement. This is reason for success of arthropods.

Introduction: Endoskeleton is the internal framework of the body. Examples: Spicules in Sponges. Calcareous plates (ossicles) in echinoderms Bones in vertebrates.

Mineralized tissues in vertebrates

What are mineralized tissues?

Tissues in which inorganic calcium carbonate crystals are embedded in the collagen matrix. About two-third of the living species that contain mineralized tissues are invertebrates. Examples: Gastropods Lower chordates Skeletal System of Vertebrates: Cartilage, Bone. Introduction: