Chps : Animals. Characteristics of kingdom Animalia: Multicellular Heterotrophic Most are motile Possess sense organs

Transcription

1 Chps 23-26: Animals

2 Chps : Animals Characteristics of kingdom Animalia: Multicellular Heterotrophic Most are motile Possess sense organs

3 Animal Characteristics Forms of symmetry: Radial Bilateral

4 Radial Symmetry: Having similar parts regularly arranged around a central axis

5 Bilateral Symmetry: Only equally divisible along medial plane Equal right and left halves to the body

6 Animal Characteristics Anatomical Terms: Anterior Posterior Dorsal Ventral Proximal Distal

7 Animal Characteristics Life styles: Sessile: Attached directly by the base; permanently attached or established. Motile: Capable of movement Aquatic: Lives in water Terrestrial: Lives on land Aerial: Capable of flight

8 Trend Toward Multicellularity Advantages to being large: Can eat more things Fewer things can eat you Allows for greater complexity (tissues, organs, body systems) Enables increased abilities, e.g. speed

9 Trend Toward Multicellularity Get bigger by increasing the number of cells Large animals have many cells Larger cells would be inefficient Surface area/volume ratio decreases with increasing size

10 Demo: Surface-to-volume Ratio 1 cm Surface Area = Volume = SA/Volume Ratio = Surface Area = Volume = SA/Volume Ratio = Surface Area = Volume = SA/Volume Ratio =

11 Challenges of Being an Animal Obtaining food (Eat) Avoiding predation (Avoid being eaten) Self maintenance Reproduction

12 Animal Phyla Phylum Porifera (Sponges): Simplest multicellular animals Don t t look or behave like animals Sessile, irregular symmetry No tissues or organs Full of pores & canals

13 Phylum Porifera (Sponges): Unique system of water currents Provides food and oxygen Cellular level of organization Animal Phyla

14 Phylum Porifera (Sponges): Animal Phyla

15 Animal Phyla Phylum Cnidaria (Jellyfish, Anemones, and Corals):

16 Animal Phyla Phylum Cnidaria (Jellyfish, Anemones, and Corals): Very diverse group (9000 sp.) Ancient group: longest fossil history of any metazoan; appeared ~ 550 MYA Entirely aquatic Sessile or free-swimming Radial symmetry Tissue level of organization

17 Nematocysts: stinging organelles Unique to Cnidarians Cnidocyte Coiled filament with barbs Can carry toxins (penetrants) or adhesives (glutinants) May act as lasso (volvents) cnidocyte

18 Animal Phyla Phylum Cnidaria (Jellyfish, Anemones, and Corals): Body plan: medusa or polyp

19 Animal Phyla

20 Animal Phyla Phylum Platyhelminthes (Flatworms):

21 Animal Phyla Phylum Platyhelminthes (Flatworms): Simple bilateral symmetry Simple cephalization ( Headedness ) Sensory organs clustered anteriorly For directional movement, foraging Contrast with radial design Ocelli Light-sensitive eyespots Organ-system level of organization Free living and parasitic forms e.g. Trematoda and Cestoda

22 Planaria Intestine Cerebral ganglia (brain) Auricle Lateral nerve cord Auricle Digestive diverticulum Pharynx (protrusable) Mouth

23 Platyhelminthes (Flatworms)

24 Animal Phyla Phylum Nematoda (Roundworms):

25 Animal Phyla Phylum Nematoda (Roundworms): Super-abundant in muck and soils Move by whip-like action Longitudinal muscles contract, bend body Flow-through digestive tract

26 Animal Phyla Phylum Nematoda (Roundworms):

27 Many are endoparasites e.g., hookworm, human roundworm, heartworm, elephantiasis

28 Acoelomates and Pseudocoelomates Coelom: fluid filled cavity formed within the mesoderm

29 Acoelomates and Pseudocoelomates Coelom: fluid filled cavity formed within the mesoderm

30 Animal Phyla Phylum Annelida (Segmented worms):

31 Animal Phyla Phylum Annelida (Segmented worms): Each body segment is called a somite Somites are separated internally by septa Surrounded by longitudinal and circular muscles Regionalized digestive tract includes: Esophagus: passageway Crop: temporary storage Gizzard: muscular stomach Intestine: food absorption

32 Many organs repeated in several somites Aortic arches (hearts) Nerve ganglia Excretory organs

33 Class Oligochaeta: Earthworms > 3000 spp. Hermaphroditic: Sperm exchanged between two individuals

34 Earthworm Anatomy Aortic heart Seminal Vesicle Esophagus Pharynx Brain Prostomium Seminal Receptacle Longitudinal nerve cord Ventral blood vessel Nephridia

35 Class Polychaeta: Marine Worms > 10,000 spp. Many long hairs Setae usually form large bundles 1 pair of paddle-like parapodia per segment For locomotion, fanning water, or as gills Parapodium Setae No clitellum