1. Kingdom Animalia

3. Characteristics Multicellular Eukaryotic cells lacking cell walls
Diploid (with the gamete being the only haploid cell)
Heterotrophs- digest in an internal cavity (enteron)
Locomotive as they search for food
Develop from an embryonic stage (blastula forms germ layers)

4. Zygote to Blastula

5. Classification based on
Symmetry
Body layers
Body cavities
Segmentation

6. Symmetry

7. Body layers

10. Body cavities
More advanced organisms have an additional body cavity called coelom- this is a fluid filled space in the mesoderm that divides the muscles of the gut from the body wall.
Coelomic fluid under pressure gives surrounding muscles something to contract against and functions as a hydrostatic skeleton

12. Advantages of body plan
Peristalsis can be developed
Locomotion
Development of internal organs

13. Segmentation
In coelmate animals the mesoderm becomes divided to form small, similar segments (somites)= metameric segmentation

14. Phylum Cnidaria

15. Organisms in the phylum Cnidaria
Include sea anemones, jellyfish, corals and freshwater Hydra.

16. Structure of Hydra
Diploblastic- endoderm and ectoderm (seperated by jelly like mesoglea)
Digestive cavity (enteron) is sac like
Enteron has only one entrance which, through called the mouth, also serves as the exit for undigested remains
Radially symmetrical so can respond to environment through 360˚
Tentacles with stinging cells (cnidocysts) in the ectoderm
Body supported by aqueous medium and hydrostatic skeleton formed by fluid filled enteron
Often sedentary but can undertake cartwheel movements

17. Feeding in Hydra Predates live prey such as daphnia
When prey touches a cnidocyst, its poison tube with barbs shoots out, impaling the prey
Paralysed animal conveyed to mouth and into enteron by tentacles
Endodermal cells secrete enzymes so digestion is initiated extracellularly
Partially digested food fragments are ingested into endodermal cells by endocytosis and digestion is completed intracellularly by lysosomes
Undigested food egested through the mouth

18. Phylum Platyhelminthes (AKA Flatworms)

19. Structure of Planarian (a platyhelminth)
Triploblastic
No coelum (acoelmoate)
Dorso-ventrally flattered =large SA:V
Gut cavity has single opening
Branched gut (reaches all parts of body)
No circulatory system
Bilaterally symmetrical
Supported by aqueous
medium although mesoderm
has a supportive role
Gliding movements by cilia

20. Feeding in a Planarian Most are detrivores but some are carnivores
Once in contact with food, they evert a pharynx by which food is taken to the gut
Enzymes secreted so initial digestion is extracellular
Partly digested fragments ingested by endodermal cells and digestion is completed intracellularly
Highly divided gut means short transport distances
Undigested food excreted through mouth

22. Phylum Annelida

23. Structure of an earthworm
Triploblastic
Coelomate
Coelom is large and filled with fluid= hydrostatic skeleton and room for development
Through gut with mouth and anus
Bilaterally symmetrical
Metamerically segmented
Locomotion via chaetae
Long and thin to allow for ease of movement

25. Feeding in an Earthworm
Detrivores
Ingested via mouth
One way gut- food drawn into a muscular pharynx, along oesophagus to be stored in the crop, slowly released into the muscular gizzard where it is crushed, then digested and absorbed in the intestine.
Allows food to be ingested continually
Digestion is completed in the gut (extracellularly)
Products of digestion are absorbed into and distributed b a well developed blood system
Undigested material excreted through anus = worm casts.

26. Animal Development Crash Course Clip
11.5 mins