dash through AK Flashcards
A whistle-stop tour of the Animal Kingdom Basic phylogeny Definitions of: Eumetazoa Bilateria Deuterostomia Protostomia Ecdysozoa Spiralia Lophotrochozoa
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see desktop for major divisions to remember
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‘ur-metazoan’
- Hypothetical last common ancestor of all animals
- First multicellular animal
- Eukaryote multicellular
- Flagellate
- Marine
- Two cell layers
- No symmetry
- c. 600 million years ago
Eumetazoa (non-bilateral animals)
porifera
6 points
- Porifera
- Sponges
- Two layers of cells
- No tissues or organs
- No nervous, digestive, or circulatory systems
- No symmetry
Eumetazoa (non-bilateral animals)
Placozoa
2 points
- Possibly close to the “ur-metazoan”
2. Two layers of cells
Eumetazoa (non-bilateral animals)
Coelenterates
Former term for Cnidaria + Ctenophora
Now recognised as paraphyletic
Eumetazoa (non-bilateral animals)
Ctenophora
5 points
- “comb jellies”
- Radial symmetry
- Two layers of cells
- Unique colloblast cells
Sticky, used in prey capture - Swim using cilia
Eumetazoa (non-bilateral animals)
Cnidaria
- Sea anemones, corals, sea pens, “jellyfish”
- Stinging cells for prey capture
- Radial symmetry
- Two layers of cells
- Single orifice and body cavity
Bilateria
cell layers
tripoblastic
Ectoderm (epidermis and nerves)
Endoderm (digestive tract)
Mesoderm (muscle, connective tissue)
anterior and posterior
front and back
Dorsal and ventral
left and right
Bilateria
2 divisions
complete digestive tracts - separate mouth and anus
- Protostomia: “mouth first”
Blastopore becomes the mouth
Anus develops secondarily - Deuterostomia: “mouth second”
Blastopore becomes the anus
Mouth develops secondarily
Deuterostomes - Chordata
5 points
- Notochord (rigid structure for muscle attachment)
- Hollow dorsal nerve cord
- Pharyngeal slits (filter feeding organs)
- Endostyle (assists in filter feeding in basal chordates)
- Post anal tail (body after anus
Deuterostomes - echinodermata
5 points
- Sea lilies, sea cucumbers, brittle stars, sea urchins, starfish
- Bilateral as larvae, radially symmetry as adults (in some classes)
- Calcareous plates in skin
- Water vascular system
- Suspension feeders, herbivores, carnivores
Deuterostomes - hemichordata
3 points
- Enteropneusta (acorn worms)
Pterobranchia - Filter feeders
- Three-part body
protostomes - ecdysozoa
5 points
- Grow by ecdysis (i.e. moulting their exoskeleton)
- Lack locomotory cilia
- Amoeboid sperm (crawl)
- “teeth” within the foregut (basal)
- Ring of spines around the mouth (basal)
Ecdysozoa - priapulida
2 points
- Penis worms
2. Unsegmented worms
Ecdysozoa - kinorhyncha
2 points
- “mud dragons”
2. Segmented, limbless, < 1mm
Ecdysozoa - Nematoda
3 points
- Round worms
- Unsegmented
- Free living and parasitic
Ecdysozoa - Nematomorpha
2 points
- Horsehair worms
2. Larval parasites of arthropods
Ecdysozoa - arthropoda
5 points
- Exoskeleton with jointed legs
- Chelicerata: spiders, scorpions
- Myriapoda: centipedes, millipedes
- Crustacea: crabs, prawns, woodlice
- Hexapoda: mayflies, wasps, true bugs
Spiralia
- Named after spiral cleavage of the embryo
- Otherwise defined as lacking the attributes of the Ecdysozoa
- Validity as a group confirmed with genetic studies
Gnathifera
5 points
- “Jaw-bearers”
- Chaetognatha
Arrow worms
Predatory, dart-shaped - Rotifera
Wheel animals
Free living and sessile species
Corona of cilia used in filter feeding and locomotion - Acanthocephala
Thorny-headed worms
Parasitic involving at least 2 hosts - Gnathostomulida
Jaw worms
Platyhelminthes and Gastrotricha
6 points
- Flatworms
- No body cavity
- No circulatory or respiratory organs
- Blind-ended digestive system
- Free living
- Parasitic (tapeworms, flukes)
Lophotrochozoa
- Clade established on molecular evidence
2. Trochophore (“wheel-carrying”) larvae
Lophotrochozoa
Annelida
4 points
- Segmented worms
- Repetition of internal organs (in each segment)
- Chitinous setae (bristles on body
- Polychaeta – bristle worms
Clitellata – earthworms and leeches
Echiura – spoon worms
Sipuncula – peanut worms
Lophotrochozoa
Mollusca
4 points
- Muscular foot
- Mantle that secretes a shell
- Toothed radula
- Gastropoda: snails, limpets, slugs
Bivalvia: clams, oysters, scallops
Cephalopoda: octopus, squid
Polyplacophora: chitons
Scaphopoda: tusk shells
Lophotrochozoa
Brachiopoda
3 points
- Lamp shells
- Dorsal and ventral valves (unlike left-right valves of Mollusca)
- Filter feeders
Lophotrochozoa
Phoronida
2 points
- Horseshoe worms
2. Filter feeders
Lophotrochozoa
Entoprocta and Ectoprocta
3 points
- Entoprocta
No body cavity - Ectoprocta
Moss animals or Bryozoa
Zooids have different functions – not truly independent animals
Some have exoskeletons - Superficially similar
Filter feeders using a ‘crown’ of tentacles
Colonial
Lophotrochozoa
Nemertea
4 points
- Ribbon worms
- Circulatory system
- Free living, carnivorous
Eversible proboscis used for food capture, toxic secretions - Move via external cilia
Lophotrochozoa
Nemertea
4 points
- Ribbon worms
- Circulatory system
- Free living, carnivorous
Eversible proboscis used for food capture, toxic secretions
- Move via external cilia