Biodiversity – Oct. 10/12
- Bilateria – Deuterostomia: Synapomorphies are specialized embryonic development and DNA
sequence data. Groups that are branches of deuterostomia include Echinodermata (ex. starfish) and
chordata (ex. cheetah).
- Bilateria – Deuterostomia – Echinodermata: These are seemingly simple organisms, but they share
much of our DNA. Includes starfish, sea urchins, and sand dollars. They are marine only. Many
burrow in sand and other materials.
- Echinoderms: Immature forms have distinct bilateral symmetry. Bilateral symmetry means there is
only one way to cut it while having identical sides. Adults appear to have radial symmetry, but it is
actually unique pentaradial symmetry. If it’s radial, then it’s a reversal. They have distinct front and
rear ends and always burrow with their front end first. They actively move around. Their mouth and
anus are separated by a complete gut.
- Bilateria – Deuterostomia – Chordata: A synapomorphy of this group is a hollow nerve cord. Includes
tunicates (hollow nerve cord in the larval stage), hagfish, and vertebrates.
- Bilateria – Deuterostomia – Chordata – Craniata: Synapomorphy is skull or cranium, and no
cartilaginous backbone. Includes hagfish and vertebrates.
- Bilateria – Deuterostomia – Chordata – Craniata – Vertebrata: Synapomorphy is vertebral column or
- Vertebrates – Sharks and rays: They have full cartilaginous skeletons, which are flexible and not as
hard as bone. Many sharks are top predators, which means they reside at the top of their food chain
with no predators of their own. They have a crucial ecological role by affecting population dynamics
of prey species.
- Vertebrates – Ray-finned fishes: There are 25,000 described species. These are the most modern fish
and the most diverse group of vertebrates. Includes sturgeon, gar, eel, herring, anchovy, carp,
goldfish, loach, minnow, piranha, tetra, catfish, electric eel, salmon, trout, smelt, lanternfish, cod,
stickleback, bass, sunfish, cichlids, gouramis, mackerel, tuna, perch, and seahorse. They are modified
and have derived/advanced fins. The largest ray-finned fish is the ocean sunfish (2000 lbs.) and the
smallest fish is 8mm long.
- Vertebrates – Tetrapods (Sarcopterygii): Synapomorphy is bone structure of fins/limbs. Fins evolved
into limbs of amphibians. Lobe-finned fish gave rise to four-legged terrestrial vertebrates.
Coelacanths and lungfishes are extant lobe-finned fishes. Fins have articulations similar to terrestrial
animal limbs. Lobe-finned fish and four-legged terrestrial vertebrates are tetrapods. This is a
monophyletic group. The cheetah is a more derived clade.
- Vertebrates – Tetrapods – Terrestrial ver