6 characteristics blastula

Transcription

1 Animals

2 Characteristics The animal kingdom is divided into approximately 35 phyla with diverse species. However, all organisms in the animal kingdom share these 6 characteristics Eukaryotic Lack cell walls Multicellular Heterotrophs Motile (at some point in their life cycle) Form a blastula (hollow ball of cells) during embryological development

3 Evolution Animals have a similar evolutionary history to plants that traces the movement of ancestral organisms from water onto land.

4 Evolution Body Plans Each species has a unique pattern and structure of body formation. The major phyla of animals have key characteristics to their body plans. Levels of Organization Cells are the simplest level of organization in animals but they can specialize to form tissues. Groups of tissues can form organs which can work together in organ systems

5 Evolution Body Symmetry The body symmetry of an animal can give indication of its classification, phylogeny, and function Symmetry can be divided into three categories: Asymmetrical No symmetry at all Radial symmetry Symmetrical across a central axis and have no real front, back, or head Bilateral symmetry Symmetrical mirror image right and left sides. Generates the following distinctions: Anterior and posterior (head and tail) ends Dorsal and ventral (back and bottom/front) surfaces Lateral (right and left) sides

6 Evolution

7 Evolution Embryological Development Animals reproduce through the formation of a zygote when a sperm fertilizes an egg. The zygote then divides until a hollow ball of cells develops. This is the blastula. Cells will start infolding a one spot in the ball, forming a tube that connects both ends. This eventually develops into the digestive tract.

8 The hole formed where the infolding began is known as the blastopore. This can develop into either the mouth or the anus. If it develops into the mouth, the animal is a protostome If it develops into the anus, the animal is a deuterostome

9 Evolution Segmentation: Repeating parts Many animals demonstrate segmentation which is the dividing of the body into segments. Examples: Earthworms and other insects Limbs: Legs, Flippers, and Wings Animals with bilateral symmetry tend to have paired limbs and cephalization (development of a distinct head with sense organs) Examples: antennae, mouthparts, wings, gills, legs, fins, arms

10 Concept Check What characteristics do all animals have? What types of symmetry are found in animals? Describe the embryological development of an animal. Include the terms zygote, blastula, protostome, and deuterostome in your answer.

11 Invertebrates Greater than 98% of animals are invertebrates Invertebrates are animals that lack a backbone

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13 Vertebrates Vertebrates are animals with a scull and a backbone, which is composed of segments known as vertebrae We are mostly familiar with vertebrates because they are the animals with which we commonly associate E.g. pets (cats, dogs, reptiles, birds), livestock (cows, pigs, sheep), etc. Vertebrates include fish, amphibians, reptiles, birds, mammals, and humans.

14 Evolution of Vertebrates The evolutionary relationships between vertebrates are shown on the next slide This was constructed using a combination of anatomical, molecular, and fossil evidence. The branching points show the evolution of major derived traits. Hinged jaws wider variety of prey Lungs buoyancy and possible ability to breathe on land Tetrapod four-footed for land motility Amniotic egg waterproof egg with shell for reproduction on land Feathers modified scales as insulation for heat conservation

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16 Concept check Which phylum has the simplest animal? What two general categories are often used to classify animals? What is the main difference that divides these categories? What are three evolutionary steps in vertebrates? What is the significance of each?