Download File - Classes with Mrs. Sheetz

Chapter 26: Kingdom Animalia I
Phylum Placozoa
Phylum Porifera
Overview
• Vertebrate:
-animal with a backbone
-50,000 species
• Invertebrate:
-animal without a backbone
-950,000 species
• Classified according to similar structures and
functions
• Common characteristics for organisms in
Animalia:
-eukaryotes
-reproduce sexually
-multicellular
-cells organized into tissues
-heterotrophic
-storage of carbohydrates as glycogen
-no cell walls
-extracellular matrix
-mobile with specialized muscle and nerve tissue
-needs oxygen
Body Structure and Symmetry
• Bilateral symmetry: right half looks like the left
half
• Radial symmetry: line drawn through middle
in any plane results in symmetry
(ex: jellyfish – aquatic animals)
• Cephalization: high concentration of sensory
tissues(eyes, ears, brain) in the anterior region
• Directions: ventral/dorsal, anterior/posterior
Tissues
• A group of cells that all function in a similar
way.
• Examples in animals: connective, epithelial
muscle, and nervous.
Germ Layers
• Fertilization: haploid egg fuses with haploid
sperm and forms diploid zygote.
• Mitosis occurs millions of times and the zygote
forms an embryo.
• Next form germ layers:
1. ectoderm
2. mesoderm
3. endoderm
(note: Cnidarians and ctenophores form from only 2 germ layers)
Gestation: the developmental period of an
organism which begins after fertilization.
Segments
• Most animals show a repeating unit
-called segmentation
Coelom
• Presence of a body cavity
Multicellular with tissues in 2 layers: Placozoa
and Porifera
Multicellular, tissues in 2 layers, radial
symmetry: Cnidaria, Ctenophora
Embryonic Development
• Morphogenesis: the study of the development of the
embryos.
• Cleavages: mitotic cell divisions
• Zygote: diploid cell formed between sperm and egg
• Blastula: the embryo consisting of 64 cells
-cavity inside called blastocele
• Gastrula: results from blastula growing and folding in
on itself.
-cavity inside called archenteron
• Develops 2 distinct germ layers, endoderm &
ectoderm, and most develop the mesoderm
*see chart on page 561 for structures produced by
germ layers
• Neural tube: formed by a rapidly dividing fold
of tissue from the ectoderm
• neurulation: the pinching and forming of the
neural tube
• Becomes the brain and spinal cord
• Notochord becomes
the vertebrae of the
spinal column.
Development Patterns
• Direct development: the immature form looks
like a miniature version of the mature form.
• Indirect development: has an intermediate
stage between the immature and mature
organisms. Do not look similar at this point.
-see frog p.562
Vertebrates and Invertebrates
• Main difference – vertebrates have a spinal
column and invertebrates do not.
• See chart on page 563
Phylum Placozoa
• Smallest phylum in Animalia
• One species
• Multicellular in 3 layers
Phylum Porifera
•
•
•
•
•
•
Sponges – simple animal not a plant
>10,000 species
Sessile – don’t move
Diagram page 565
Gemmule – asexual bud
Also sexually reproduces