UNIT 2: KINGDOM ANIMALIA 1 (27) Flashcards
General features of kingdom animalia:
1) Multicellular
2) Heterotrophs
3) No cell walls
4) The ability to move
5) All symmetries
6) All habitats
7) Ability for sexual reproduction, diplontic life cycle (diploid multicellular condition)
8) Specific embryonic development that leads to germ layers and tissue types
General features of kingdom animalia (2):
- Part of Opisthokonta
- Sister group with choanoflagellates: share similar DNA, modern sponges have cells very similar to modern choanoflagellates
Five key transitions can be noted in animal evolution:
1) Tissue development
2) Symmetry
3) Body cavity formation
4) Segmentation
5) Embryo development differentiation
Parazoa
- Para = next to
- Zoo = animal
- Lack defined tissues and organs
- Have the ability to dedifferentiate and re-differentiate their cells
Eumetazoa
- Eu = true
- Meta = late
- Zoo = animal
- Have distance and well-defined tissues
- Have irreversible differentiation for most cell types
- Diploblast vs. Triploblast
Diploblast
- Di = two
- Blast = to spout
- Two cell layers
Ectoderm
- Ecto = outside
- Non-cellular middle
- Endoderm
Evolution of symmetry
- Parazoa have no symmetry and Eumetazoa does have symmetry
Radial symmetry
- Symmetry around a central axis (EX: starfish or a tulip flower)
- Body parts arranged around central axis
- Can be bisected into two equal halves in any 2-D plane
Bilateral Symmetry
- When the body plan of an animal can be divided along a line that separates the animal’s body into right and left halves that are nearly identical of each other
- Bi = two
- Lateral = side
- Only one mirror image
- Other directional bisections
- Directional movement
- Leads to cephalization
Cephalization
- The development of sense organs near the front, also known as the head (an organism with a well-developed head is known as highly cephalized)
- Cephalo = head
Evolution of the a body cavity:
- Eumetazoa may produce coelom (the body cavity in metazoans)
- =cavity, sounds like ‘seal’
- Space in between tissues, surrounded by mesoderm
Acoelomate
- No coelom
- A = without
Pseudocoelomate
- Coelom between mesoderm and endoderm
- Pseudo = false
Eucoelomate
- Coelom lined on both sides with mesoderm
- Eu = true
Evolution of segmentation
- Segmentations caused by Hox genes
- Provides three advantages:
1) Redundant systems and tissues
2) Improved locomotion
3) Regional specialization
Blastula
- an animal embryo at the early stage of development when it is a hollow ball of cells
- Occurs through cell division (cleavage)
- A hole forms in the blastula called a blastopore
- Blast = to sprout
- Pore = hole
- Blastopore initiates digestive system development
Protostome
- A multicellular organism whose mouth develops from a primary embryonic opening
- Aka if the blastopore become the south
- Proto = first
- Stoma = mouth
Phylums that have protostome
- Annelids, arthropods, mollusks, nemerteans nematodes, platyhelminthes, rotifers, tardigrades
Deuterostome
- The blastopore (the first opening in cleavage) developing into the anus during embryonic development
- Aka if the blastopore becomes the anus
- Deutero = second
Animals with deuterostomes
- Chordates
- Echinoderms
Protostome/Deuterostome Differences #1:
1) Cleavage pattern of embryonic cells
- Protostomes = spiral cleavage
- Deuterostomes = radial cleavage
Protostome/Deuterostome Differences #2:
2) Development fate of cells
- Protostomes = determine development
- Deuterostomes = indeterminate development
Protostome/Deuterostome Differences #3:
3) Origination of Coelom
- Protostomes forms simply and directly from splitting the mesoderm called schizocoely
- = split cavity
- Deuterostomes forms indirectly from outpocketing of the gut called enterocoely
- = stomach cavity
Cambrian Explosion
- The time when most of the major groups of animals first appear in the fossil record and resulted in the divergence of most modern metazoan phyla
- 542-488 million years ago marks the most rapid evolution of new animal phyla and animal diversity in Earth’s history
- The curse of the Cambrian Explosion is still debated
- Increasing O2
- Increasing oceanic Ca
- Broad continental shelf
- Hox genes
The Hox developmental gene complex evolved:
- It provided a tool that can produce rapid changes in body plan
- Serve as “master control genes” that can turn on or off numbers of other genes
- Encode transcription factors that control the expression of humorous other genes
- Hox genes are homologous across the animal kingdom
- Genetic sequences are similar across most animals, presence in a common ancestor
Phylum Porifera
- Sponges
- Pore = hole
- Fer = bearing
- They are parazoans
- No tissue and no symmetry
- Include marine and freshwater species
Phylum Porifera Reproduction
- Asexual reproduction = fragmentation
- Sexual reproduction = egg and sperm meet
Phylum Porifera Movement:
- Sponge larvae are ciliated/flagellated and able to swim
- Adults are non-motile and attached to a substratum
Phylum Porifera Cell Types:
- Inner layer = specialized flagellated cells called choanocytes
- Choana = collar
- Cyte = cell
- Central layer = gelatinous protein-rich matrix called the mesohyl
- = middle matter
- Spicules and spongin
Phylum Porifera Filter Feeders:
- Choanocyte flagella draws water/particles/small animals though numbers small pores
- Intracellular digestion
- Intra = within
- Eventually exits from the osculum (a large hole in a sponge through which water leaves from)
Phylum Cnidaria Animals:
-Hydroids
- Man O’ Wars
- Sea anemones
- Corals
- Jellyfish
- Box jellyfish
Phylum Cnidaria Body Plan:
- Radial symmetry
- Central mouth/anus wreathed with tentacles
Phylum Cnidaria Diploblasts:
- Ectoderm and endoderm layers are cellular with tissue
- Middle is made up if non-tissue jelly ir mesoglea
- = middle glue
Phylum Cnidaria Facts:
- 99% are marine species
- Dimorphic: 2 body forms (occurring in or representing 2 body forms)
- Medusa and polyp
- Same tissues in both
- Basically flipped over versions of one another
Phylum Cnidaria Lifecycle:
- Polyps may be solitary or branch their guts to form colonies
- Polyps can bud to asexually reproduce
- Some groups alternate between polyps and medusas
Medusa
- A reproductive stage that creates sperm/ egg and grow off of gonozooid polyps
Cnidarians Specialized Cells:
- Cnidarians have unique specialized cells on their epidermis called cnidocyte
- Cnido = nettle = to sting
- Cyte = cell
Cnidarians Nematocysts:
- Large stinging organelles called nematocysts
- Nema = thread
- Cyst = sac
- Contain barbs at the base of a long coiled thread
- Hair-like projection extends to outside the cell and sensitive to tactile stimulation
- Mostly carnivorous
Nematocysts Digestion:
- Extracellular digestion
- Extra = outside
- Digestion veins with fragmentation in the gastrovascular cavity (humans do this too)
- No circulatory, respiratory, or excretory systems
