KINGDOM ANIMALIA

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The Big Picture

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Part A – Animal Characteristics

DEFINING CHARACTERISTCS OF ANIMALS1. Heterotrophs: ingest their food2. Multicellular: 3. Eukaryotic: animal cells with a nucleus and organelles – large diversity of cell specialization4. No cell walls TWO MAIN DIVISIONS:

Invertebrate: all other phyla without internal skeletons

Vertebrate: Phylum Chordate – internal skeleton

Level of Organization

Cellular – Porifera

Tissues – Cnidaria

Organs- all others

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Cephalization Cephalization is considered an evolutionary trend,

whereby nervous tissue, over many generations, becomes concentrated toward one end of an organism. This process eventually produces a head region with sensory organs.

Cephalization is intrinsically connected with a change in symmetry. It accompanied the move to bilateral symmetry made in flatworms, with ocelli and pinnae placed in the head region.

In addition to a concentration of sense organs, all animals from annelids on also place the mouth in the head region.

This process is also tied to the development of an anterior brain in the chordates from the notochord.

A notable exception to the trend of cephalization throughout evolutionary advancement is phylum Echinodermata, which have Pentamerous Radial Symmetry – Echinoderm Adults only

Symmetry

None – Porifera

Radial – Cnidaria

Bilateral – All others

› Pentamerous Radial Symmetry – Echinoderm Adults only

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Tissue Layers

• Endoderm - digestion and respiration structures

• Mesoderm - muscles, bones, blood, and reproductive organs

• Ectoderm - skin, brain, and nervous system

Tissue Layers

None – Porifera

Diploblastic – Cnidaria endoderm & Ectoderm with mesoglea between

Triploblastic – All others Endoderm, Mesoderm, Ectoderm

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Development of a Coelom

Diploblastic Acoelomate – Cnidaria

Triploblastic Acoelomates – Platyhelminthes

Pseudocelomate – Nematoda

Coelomates – Annedlida and everything above

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The Acoelomates

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DigestiveCavity

DigestiveLining

SolidTissue

Body Wall

No cavity between body wall & digestive tract

Cnidaria

The Pseudocoelomates

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Digestive Cavity

Digestive Tract

Pseudocoelom

Body Wall

Body cavity partially lined with mesoderm

Partial Lining

Nematoda

The True Coelomates

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Digestive Cavity

Digestive Tract

Coelom

Body Wall

Body cavity completely lined with mesoderm

Complete Lining

Annelida

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Embryological Development

Bilateral animals can be divided into two main groups based on embryological development

Protostomes› Body cavity forms within a space between the body

wall and the digestive cavity› Blastopore becomes mouth› e.g. nematodes, arthropods, flatworms, annelids,

mollusks Deuterostomes

› Body cavity forms as an outgrowth of the digestive cavity

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Protostome vs Deuterostome

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Protostome

•Coelom forms from the solid masses in the embryo•blastopore becomes the mouth

• spiral / determinate cleavage

• mosaic development

(Annelida, Arthropoda, Mollusca,)

Deuterostome

• Coelom forms from a portion of the digestive tube•blastopore becomes the anus

• radial / indeterminate cleavage

• regulative development

(Echinodermata, Chordata)

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Symmetry

Reproduction

5. Reproduction: Asexual and sexual A. Direct development: “Babies”

(offspring) look like adults (they get bigger as they get older, but don’t change)

B. Indirect development: Metamorphosis Ex) Tadpole to frog

Feeding

Herbivores: Eats plants Carnivores : Eats animals Omnivores : Eats plants and animals Parasites : Lives off of a host Filter Feeders : Strains floating plants and

animals from surrounding water Detrivores : Feeds on decaying plants and

animals (detrius)

The 7 Essentials

Feeding – see above Respiration – skin or full system Internal Transport – closed or open

circulation Excretion – waste removal Response – nerve cells – brain-

specialized organs Movement – exo or endoskeleton,

muscles Reproduction – sexual or asexual

Sponges_Phylum Porifera

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Sponges_Phylum PoriferaKey Ideas

Simplest Animal - Commonly referred to as Sponges

Adults are sessile- can’t move on their own

Lack true tissues and organs, most are unspecialized – Cell Level of Organization

Incomplete digestive system No Symmetry Ancient & mostly marine Close to 5,000 species divided into 3

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Porifera

Outer layer protects the interior and has many holes through which water can enter the sponge

Inner layer are lined with collar cells, which have flagella

Amoebocytes wander through the jelly-like material and pick up food from the collar cells for digestions, transport oxygen, dispose of waste and can change into other cells for support

Have special chemical defenses to protect from predators, disease organisms, humans use these chemicals

Related closely to protists and are the earliest animals.

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Porifera Cell Types

Porocytes: water goes thru them into central cavity

Collar Cells: move water current thru the pores via flagella

Osculum: opening that water exits cavity thru Spicules: form skeleton

Some sponges have skeletons made by both CaCO3 and SiO2.

Amebocytes: build the spicules

Note: water flow = nutrients in and waste out

Feeding

Filter Feeders! Sponges are characterized by the possession of a

feeding system unique among animals. Poriferans don't have mouths; instead, they have tiny pores in their outer walls through which water is drawn. Cells in the sponge walls filter goodies from the water as the water is pumped through the body and out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of chambers connected by a series of canals. Sponge cells perform a variety of bodily functions and appear to be more independent of each other than are the cells of other animals.

Reproduction

Sexual: - sperm are release into the water thru pores amebocytes carry to eggs zygote larvae swim & settle new sponge

Asexual: Gemmules: sphere of amebocytes &

spicules that can survive freezing or drying

Budding: part falls off new sponge

Phylum Cnidaria

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Phylum Cnidaria: the hydra, anemones, & jellyfish – Radial symmetry

› Tissue Level of Organization - Cells organized into distinct tissues

› Rudimentary nerve network and contractile tissue› No true organs› Incomplete Digestive System - One digestive

opening › Reproduce sexually and asexually

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Cnidarians- Con’t

Radial symmetry, most do not have a head and are sessile

Tentacles with stinging cells called cnidocytes

Has poisonous barbs called nematocysts, that fire when touched, once prey has been captured, the tentacles move it to the gastovascular cavity

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Two forms Polyp-cylindrical

body with tentacles radiating from one end, sessile

Medusa- umbrella shaped form with fringed tentacles on the lower edge, move freely

Some cnidarians exist in both forms and some one or the other

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Types of Cnidarians Hydrozoa- sessile polyps & medusa

stages – often found in colonies – hydra, man-of-war

Scyphozoa- mostly medusa, v short polyp – some very toxic - jellyfish

Anthozoa- only polyp - sea anemones & most corals

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