Adapted from Lesser Known Protostome
Phyla. SICB 2001. J.R. Garey.
Porifera
Cnidaria
Ctenophora
Platyhelminthes
Gastrotricha
Gnathostomulida
Cycliophora
Rotifera
Annelida
Mollusca
Sipuncula
Nemertea
Bryozoa
Brachiopoda
Phoronida
Arthropoda
Onychophora
Tardigrada
Nematomorpha
Nematoda
Priapulida
Kinorhyncha
Loricifera
Echinodermata
Hemichordata
Chordata
Tardigrada
http://www.solutionassoc.com/Fun/Fun.html
Tardigrada: “water bears”
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First discovered in 1773
800 spp
0.1-0.5mm in length
Widespread
Live in semi aquatic habitats, water film
Cryptobiotic, some are cyclomorphic
– Temp range from +149C to -272C, withstand high
vacuum, high UV, long periods without O2
– Dessication for > 120 years: back to life in hours
Tardigrada
• Metameric body plan
• Toes on each leg with intrinsic
musculature (cf onychophoryans)
• Walk with muscles, not with hydrostatic
skeleton
• Oral stylets pierce plant cell walls
– Diets specialized for predation, herbivory,
detritivory
• Internal fertilization, shed cuticle with eggs
Adapted from Lesser Known Protostome
Phyla. SICB 2001. J.R. Garey.
Porifera
Cnidaria
Ctenophora
Platyhelminthes
Gastrotricha
Gnathostomulida
Cycliophora
Rotifera
Annelida
Mollusca
Sipuncula
Nemertea
Bryozoa
Brachiopoda
Phoronida
Arthropoda
Onychophora
Tardigrada
Nematomorpha
Nematoda
Priapulida
Kinorhyncha
Loricifera
Echinodermata
Hemichordata
Chordata
Onychophorans: velvet worms
Onychophorans
• Discovered in 1826
• 110 spp, 5mm-15 cm
• Extant spp all terrestrial
– Humid habitats only
– Cuticle thin (no Ca), permeable
• 13-43 pairs of sac-like legs
• Metameric
– little tagmatization
– little cephalization
• Annelid/arthropod link
– Head ~ polychaete
Oral “slime”
papillae
• Predaceous
• Spray adhesive goo from slime glands
(modified nephridia) to entangle prey
• Gas exchange by trachea, spiracles
– Not homologous to arthropod trachea
• Reproduction:
– Ovoparity, viviparity, ovoviviparity
Arthropoda
Mollusca
Chordata
Platyhelminthes
Nematoda
Annelida
Porifera
Echinodermata
Other
Sarcomastigophora
Apicomplex
Ciliophora
Phylum Arthropoda
• Arthro = joint, poda = feet
– Refers to hard, chitinous exoskeleton
• “Terrestrialized” annelid body plan
• Metameric
• Tagmatized:
– head, thorax, abdomen
– cephalothorax, abdomen
– prosoma, opisthosoma
• Cephalized
– Compound eyes, antennae (mechano- &
chemosensory)
P. Arthropoda
Modern crustacea
Trilobita
Cenozoic (65-present)
Mesozoic (251-65 mya)
Paleozoic (542-251 mya)
Crustaceamorph stem line
Precambrian (>542 mya)
Phylum Arthropoda
• Subphylum Trilobita
• SubPhylum Chelicerata
– Class Merostomata – horseshoe crabs
– Class Arachnida – spiders, ticks
– Class Pycnogonida – sea spiders
• Subphylum Hexapoda
– Class Entognatha
– Class Insecta …!!
• SubPhylum Crustacea
– 6 subclasses
Phylum Arthropoda
Subphylum Trilobita
• Common 500 mya (4000 spp) but extinct
by 225 mya
• Each body segment had a biramous
appendage (inner for walking)
• 3 body tagma
• Compound eyes with ommatidia
Subphylum Chelicerata
• Include spiders and mites and daddy LL,
scorpions, horseshoe crabs
• Lack antennae
• 1st pair of appendages on the prosoma =
the chelicerae (adapted for feeding)
Class Merostomata
• 4 spp, all marine
• Not true crabs (i.e., not crustaceans)
• head + thorax = prosoma or
cephalothorax
• appendages of opisthosoma flattened to
become “book gills” for gas exchange
Telson
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