Introduction to Animal Diversity Packet #76 Chapter #32

Animal Diversity Biologists have identified 1.3 million living species if animals. Biologists have identified 1.3 million living species if animals. Estimates put the range much higher Estimates put the range much higher 10 – 200 million 10 – 200 million Evolutionists believe that the chanoflagellates, a colonial flagellated protist, was the start of Kingdom Animalia. Evolutionists believe that the chanoflagellates, a colonial flagellated protist, was the start of Kingdom Animalia.

Characteristics Most Common to Animals Eukaryotic Eukaryotic Multicellular Multicellular Heterotrophic Heterotrophic Animals use enzymes to digest their food after they have ingested it. Animals use enzymes to digest their food after they have ingested it. Stores energy as fat (long term) or as glycogen (short term) Stores energy as fat (long term) or as glycogen (short term)

Reproduction in Animals

Reproduction—The Obvious Most animals reproduce sexually and have a diploid stage that is dominant in the life cycle. Most animals reproduce sexually and have a diploid stage that is dominant in the life cycle. Sperm and egg unite to form a zygote Sperm and egg unite to form a zygote Zygote undergoes cleavage Zygote undergoes cleavage Multiple cell divisions result in the development of a hollow ball of cells Multiple cell divisions result in the development of a hollow ball of cells Blastula Blastula Blastula undergoes gastrulation. Blastula undergoes gastrulation. Embryonic tissues are formed Embryonic tissues are formed Developmental stage is called the gastrula. Developmental stage is called the gastrula.

Reproduction—The Sometimes Not So Obvious Some animals develop directly into adults Some animals develop directly into adults After transient stages of maturation After transient stages of maturation However, life cycle of many animals include larval stages. However, life cycle of many animals include larval stages. Larva Larva Sexually immature form of an adult Sexually immature form of an adult Morphologically distinct Morphologically distinct Usually eats different food Usually eats different food Inhabits different areas than the adult Inhabits different areas than the adult Must undergo metamorphosis to become an adult Must undergo metamorphosis to become an adult

Developmental Genes Across Kingdom Animalia Animals share a unique homeobox Animals share a unique homeobox Family of genes Family of genes Hox genes Hox genes The number of hox genes is correlated with the complexity of the animal’s anatomy. The number of hox genes is correlated with the complexity of the animal’s anatomy.

Categorizing Kingdom Animalia Animals are classified on major features of animal body plans. Animals are classified on major features of animal body plans. Symmetry Symmetry Tissue Complexity Tissue Complexity Cephalization Cephalization Body Cavities Body Cavities

Body Plans Symmetry

Introduction There are two types of symmetry There are two types of symmetry Radial Symmetry Radial Symmetry Bilateral Symmetry Bilateral Symmetry

Symmetry Radial Symmetry Radial Symmetry Describes how the parts of an animal radiate from the center. Describes how the parts of an animal radiate from the center. Any imaginary slice through the central axis divides the animal into mirror images. Any imaginary slice through the central axis divides the animal into mirror images. Sea anemones have a top (oral, mouth) side and a bottom (aboral) side. Sea anemones have a top (oral, mouth) side and a bottom (aboral) side.

Symmetry II Bilateral Symmetry Bilateral Symmetry Describes a two sided body plan. Describes a two sided body plan. Animal has a left side and right side Animal has a left side and right side Imaginary slice can only be placed in one location in order to divide the animal mirror images. Imaginary slice can only be placed in one location in order to divide the animal mirror images. Lobster has a dorsal (top) side, a ventral (bottom) side, a left and right side, an anterior (head) with a mouth and a posterior (tail) end. Lobster has a dorsal (top) side, a ventral (bottom) side, a left and right side, an anterior (head) with a mouth and a posterior (tail) end.

Symmetry III Animals can be categorized according to the symmetry of their bodies or lack of it. Animals can be categorized according to the symmetry of their bodies or lack of it. Symmetry Reflects Lifestyle Symmetry Reflects Lifestyle Radial animals are sessile or planktonic Radial animals are sessile or planktonic Bilaterial animals more actively from one place to another Bilaterial animals more actively from one place to another The nervous system enables these organisms to move. The nervous system enables these organisms to move.

Tissue

Tissue I As a young embryo develops, embryonic tissue, called germ layers, are produced via gastrulation. As a young embryo develops, embryonic tissue, called germ layers, are produced via gastrulation. There are three germ layers There are three germ layers Ectoderm Ectoderm Endoderm Endoderm Mesoderm Mesoderm

Tissue II Ectoderm Ectoderm Outer layer Outer layer Gives rise to the body covering and the nervous system Gives rise to the body covering and the nervous system Endoderm Endoderm Inner layer Inner layer Gives rise to the lining of the gut (archenteron) and other digestive organs Gives rise to the lining of the gut (archenteron) and other digestive organs Mesoderm Mesoderm Middle layer Middle layer Gives rise to most other body structures. Gives rise to most other body structures. Including muscle Including muscle

Diploblastic vs. Triploblastic Diploblastic Diploblastic Animals with only two layers Animals with only two layers Ectoderm and Endoderm Ectoderm and Endoderm Jellies Jellies Corals Corals Comb jellies Comb jellies Triploblastic Triploblastic Animals with all three layers Animals with all three layers Include all bilaterally symmetric animals. Include all bilaterally symmetric animals.

Triploblastic Animals & Body Cavities

Functions of Body Cavities Provides protection to internal organs Provides protection to internal organs Allow organs to grow and move independently of the outer body wall. Allow organs to grow and move independently of the outer body wall.

Body Cavity I Triploblastic animals have traditionally been classified as Triploblastic animals have traditionally been classified as Acoelomates [ey-see-luh-meyt] Acoelomates [ey-see-luh-meyt] No body cavity No body cavity Lack a coelom. [see-luhm] Lack a coelom. [see-luhm] Pseudocoelomate [soo-doh- see-luh-meyt, -si-loh-mit] Pseudocoelomate [soo-doh- see-luh-meyt, -si-loh-mit] Body cavity not completely lined with mesoderm Body cavity not completely lined with mesoderm Body cavity formed from the blastocoel. Body cavity formed from the blastocoel. Coelomate Coelomate True coelom True coelom Body cavity completely lined with mesoderm. Body cavity completely lined with mesoderm. Cushions the internal organs and protects them. Cushions the internal organs and protects them.

Formation of the Coelom [see-luhm] Coeloms can be divided into two categories based on how it is developed. Coeloms can be divided into two categories based on how it is developed. During gastrulation, developing digestive tube forms the archenteron. During gastrulation, developing digestive tube forms the archenteron. Protostomes Protostomes Development of the coelom forms from splits in the mesoderm Development of the coelom forms from splits in the mesoderm Schizocoelous Development Schizocoelous Development Deuterostomes Deuterostomes Development of the coelom forms from outpocketing of the mesodermal tissue of the archenteron. Development of the coelom forms from outpocketing of the mesodermal tissue of the archenteron. Enterocoelous Development Enterocoelous Development

The Coelomates

Introduction I Protostomia Protostomia Mollusks Mollusks Annelids Annelids Arthropods Arthropods Deuterostomia Deuterostomia Enchinoderms Enchinoderms Chordates Chordates

Protostomes Blastopore develops into the mouth Blastopore develops into the mouth Undergo spiral and determinate cleavage Undergo spiral and determinate cleavage Spiral cleavage Spiral cleavage Describes how the planes of cell division are diagonal to the vertical axis of the embryo. Describes how the planes of cell division are diagonal to the vertical axis of the embryo. Smaller cells lie in the grooves between larger, underlying cells Smaller cells lie in the grooves between larger, underlying cells Determinate cleavage Determinate cleavage Indicates that the developmental fate of each embryonic cell is determined at fertilization. Indicates that the developmental fate of each embryonic cell is determined at fertilization. If cell is isolated it will form an inviable embryo. If cell is isolated it will form an inviable embryo.

Deuterostomes Blastopore typically becomes the anus. Blastopore typically becomes the anus. Undergo radial and indeterminate cleavage. Undergo radial and indeterminate cleavage. Radial cleavage Radial cleavage Cleavage planes are either parallel or perpendicular to the vertical axis of the egg Cleavage planes are either parallel or perpendicular to the vertical axis of the egg Indeterminate cleavage Indeterminate cleavage Each cell produced by early cleavage divisions has the capacity to develop into a complete embryo. Each cell produced by early cleavage divisions has the capacity to develop into a complete embryo.

Protostomes vs. Deuterostomes

Review

Symmetry Symmetry Radial Symmetry Sea anemones Bilateral Symmetry Lobster

Tissue Germ Layers EctodermOuter layer Body Covering Nervous System Mesoderm Middle layer Muscle Other Body Structures EndodermInner Layer Lining of Gut Digestive System

Germ Layers  Body Cavity Body CavityDiploblasticTriploblasticAcoelomatesPsuedocoelomatesCoelomatesProtostomesDeuterostomes

Body Cavity CoelomatesProtostomes Blastopore  Mouth Spiral Cleavage Determinate Cleavage Deuterostomes Blastopore  Anus Radial Cleavage Indeterminate Cleavage