ANIMALS Flashcards
Animal Classification
Domain Eukarya
Kingdom Animalia
multicellular organisms - well developed tissues (one exception) animals eat other organisms - heterotrophic by ingestion - digest food in internal digestive cavity animals move
NUMBER OF PHYLA
THIS REPRESENTS 9 / 36 ANIMAL PHYLA (ABOUT 25% OF THE PHYLA, BUT 95% OF ANIMAL SPECIES)
4 key distinctions divide the animals…
- Does the animal have specialized cells that form defined tissues?
- Does the animal develop with radial symmetry or bilateral symmetry?
- During development, does the animal’s gut develop from front to back or back to front?
- Does growth occur by molting or by adding continuously to the skeletal elements?
Does the animal have true tissues?
no true tissues: sponges
true tissues: everything else
Tissues
Tissues are layers of communicating cells that work together to perform the same function
Animals are first categorized by the presence or absence of tissue, then the number of tissue layers
Parazoa: No true tissues
Eumetazoa: Two or three tissues
- Diploblast: Two tissues
- Triploblast: Three tissues
Porifera
Parazoa – No tissues About 5000 species No symmetry Sessile Filter-feeders Use choanocytes to move water in and out of spongocoel Full size sponge can filter more than 1000 gallons of water per day. Absorbent and Porous
What type of symmetry does the animal have?
Radial Symmetry: multiple planes divide the organism into mirror images
Bilateral Symmetry: only one plane divides the organism into mirror images
Symmetry
Eumetazoans are divided into two groups based on larval symmetry (adult body plan may have secondary symmetry)
Radially symmetric animals can be cut in any direction with equal portions
Bilaterally symmetric animals can only be cut into mirrored left and right sides
Cnidarians
11,000 species
Only phyla with radial symmetry (that we study)
Jellyfish, Corals, and Anemones
Defined as having stinging cells to capture prey
diploblastic – that is, the body and tentacles consist of two cell layers,
Live either as free-floating form or polyp form
Cnidarians: Corals
Corals obtain much of their nutrition from algae that live within them
- Symbiotic relationship
Coral bleaching:
When corals expel their algae, can happen due to pollution and/or climate change
Blastopore Fate
Triploblast animals form a tubular gut during the blastocyst stage
The blastopore becomes either the mouth or the anus
Name depends on fate of blastopore
- Protostomes = “first mouth”
- Deuterostome = “second mouth” (the anus develops from the blastopore first)
Protostome vs Deuterostome
Deuterostomes include Chordates and Echinoderms
Protostomes include Arthropods, Roundworms, Mollusks, Annelids, and Flatworms
Protostome Development
Protostomes are further divided based on their larval body form
Lophotrochozoans = lopho + trocho
- Lophophorata have a hollow feeding appendage (lophophore)
- Trochophores use cilia for motility
Ecdysozoa = “molting animals”
- Have exoskeleton that must be shed in order to grow (ecdysis)
Mollusca
Bilateral symmetry Triploblastic Protostomes Lophotrochozoans ~ 45,000 species
3 Classes
- Gastropoda
- Bivalvia
- Cephalopoda
Body plan:
- Viscera (gut system)
- Mantle (secretes shell)
- Muscular foot (can be modified into tentacles
Lophotrochozoans
Mollusca, Annelids
