5. Major Phyla
a. Porifera: Sponges
b. Cnidaria: Corals, Hydra, Anemones, Jellyfish
Protostomes: Lophotrochozoans
c. Platyhelminthes: Flatworms
d. Annelida: Segmented worms
e. Mollusca: Chitons, snails, bivalves, cephalopods
Protostomes: Ecdysozoans
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
- molt four times, resecreting their
cuticle each time
- complete digestive tract
- some cephalization with anterior
neural ganglion
- free living and parasitic
-human parasites: trichinosis,
filariasis, elephantiasis, Ascariasis
(two foot intestinal worms)
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
Cryptobiotic: can dehydrate to
less than 1% of normal and
endure for 10 years.
Can endure the vaccuum of space
and 6000 atmospheres of
pressure.
Thin exoskeleton, unjointed legs
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
h. Onychophora
Sister group to the Arthropods; thin exosleleton and unjointed
legs, like tardigrades
Predatory; immobilize prey by shooting glue
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
h. Onychophora
i. Arthropoda
Myriapoda
Vericrustacea
Mandibulata
Exoskeleton
Jointed legs
Crustacea
Remipedes
Hexapods
Trilobita
Arachnomorpha
Xiphosura
Chelicerata
From Regier et al. (2010)
Arachnids
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
h. Onychophora
i. Arthropoda
Arachnomorpha clade:
Includes trilobites and Chelicerates. The
chelicerates have two body regions, the
cephalothorax and abdomen. They also have
only one pair of appendages before the
mouth – usually pincers. In spiders, these
are fangs that inject poison.
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
h. Onychophora
i. Arthropoda
The Mandibulata clade:
Includes the myriapods
(centipedes and millipedes) and
crustaceans and their
descendants (the hexapods). So,
insects are the terrestrial
descendants of crustaceans.
5. Major Phyla
Protostomes: Ecdysozoans
f. Nematoda
g. Tardigrada
h. Onychophora
i. Arthropoda
So in the mandibulata clade, we see
duplication (myriapods), specialization
(crustaceans), and reduction/fusion (insects)
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
Internal skeleton composed of
interlocking plates of calcium
carbonate. A system of internal
canals fills and empties tube feet.
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
Hollow dorsal nerve cord
Pharygeal gill slits
All marine – some reach 8 ft
in length
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
l. Chordata
4 characteristics:
- hollow dorsal nerve chord
- notochord
- pharygeal gill slits
- post-anal tail
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
l. Chordata
subphyla:
Urochordata
Cephalochordata
Vertebrata
“Tunicates”: Mobile larvae, sessile filterfeeding adults - filter with the pharynx
and gill slits.
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
l. Chordata
subphyla:
Urochordata
Cephalochordata
Vertebrata
Mobile larvae, sessile filterfeeding adults - filter with the
pharynx and gill slits.
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
l. Chordata
subphyla:
Urochordata
Cephalochordata
Vertebrata
Pikaia – the earliest Chordate – dates
from the Cambrian period
5. Major Phyla
Protostomes:
Deuterostomes:
j. Echinodermata
k. Hemichordata
l. Chordata
subphyla:
Urochordata
Cephalochordata
Vertebrata
“Jointed spine” – vertebrae.
Although Hagfish lack this, so
sometimes the group is called
Craniata (has a skull)
Patterns in evolution:
Innovation, radiation, competitive contraction
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Hyperoartia: “Jawless fishes” Lampreys and Hagfish
Lamprey larvae look very
much like cephalochordates
5. Major Phyla
Deuterostomes:
I. Chordata
Vertebrata
Hyperoartia: “Jawless fishes”
Evolve in late Cambrian, radiate in the Ordovician
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes – Jawed Vertebrates
Move from detritivores to predators
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes – Jawed Vertebrates
The Devonian was the “Age of Fishes” – a radiation of the first jawed
vertebrates, dominated first by the Placoderms and then by
Cartilaginous and bony fishes
Arthrodires
Placoderms
Antiarchs
Chondrichthyes (Sharks, rays)
Acanthodians
Teleosts
Ray-finned Fishes
Bony Fish
Lobe-finned Fishes
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes – Jawed Vertebrates
The Devonian was the “Age of Fishes” – a
radiation of the first jawed vertebrates,
dominated first by the Placoderms and then by
cartilaginous and bony fishes
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes – Jawed Vertebrates
Bony fishes dominate today: lighter skeleton and swim bladder
Ray-finned Fishes
Lobe-finned Fishes
5. Major Phyla
Deuterostomes:
l. Chordata
Vertebrata
Gnathostomes – Jawed Vertebrates
Bony Fishes (Osteichthyes) comprise 40% of living vertebrate species