EEB267H1 Lecture Notes - Lecture 6: Rete Mirabile, Actinopterygii, Haikouella

31 views7 pages
Welcome to Osteichthyes
Cephalochordata Urochordata Haikouella Myxiniformes Petromyzontiformes
Chondrichthyes Actinopterygii Sarcopterygii calcium salts in cartilaginous
endoskeleton
jaws skull
proto-vertebrae, true gills, two eyes, olfactory lobes
many molecular characters
dorsal hollow nerve cord, notochord, post-anal tail
Surprisingly, the synapomorphy for Osteichthyes is ... the presence of a gas filled
structure called the gas bladder (the bladder looks silvery because it is covered with
guanine crystals, which makes it practically impermeable to gas leaks).
lymphocytes have unique antigen receptors
gas bladder
1
What is bone?
Another type of hard tissue composed of:a matrix of (mainly) collagen fibers and
other proteins
+hydroxyapatite crystals 3(Ca3PO4)2 .Ca(OH)2 (~ 70% of the weight, rigid,
hard)+water (~ 5%)
produced by specialized cells called osteoblasts. Blood vessels, nerve fibers run
throughout the bone in canals
Specialized cells called osteoclasts are responsible for breaking bone down. Osteoblasts
then produce new bone matrix to replace the digested area (in other words, bone can
repair itself).
2
The evolution of bone: it’s older than we thought
bone is found in a number of extinct fishes that existed before Osteichthyes originated.
This is why bone isn’t an autapomorphy for the “bony fishes”:
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in
Cephalo. Urochor. Haikouella Myxin.
[ -------- extinct jawless “fishes” --- ] [ -------- Gnathostomata --------------- ]
Petromyz.
† † † †
Chondrichthyes Osteichthyes
= loss of ability to make bone
cellular cartilage
bone
acellular cartilage
The Actinopterygii
(aktis [ray] + pteron [wing]) = ray-finned fishes
Autapomorphy for the Actinopterygii: The presence of ganoine in scales. Ganoine is
shiny, hypermineralized (~ 97% hydroxyapatite), acellular material laid down in thick,
successive layers producing “growth rings”
3
Actinopterygians, their big evolutionary innovations
......... nothing major to begin with ......... butthe ray-finned fishes are both incredibly
species-rich (at approx. 32,000 species, they are the largest vertebrate group) and
incredibly ecologically diverse.
WHAT HAPPENED TO MAKE THEM SO DIVERSE?
1. How not to sink like a rock in water
Simple physics:
Density = mass/volumeSpecific gravity = density of object/density of waterPure
water has a specific gravity of 1.0, while salt water has a s.g. of ~ 1.026 soIf your
specific gravity is > 1.0 you sink (in pure freshwater)
If your specific gravity is < 1.0 you float (in pure freshwater)
How to change your density: Chondrichthyes Solutions
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 7 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Chondrichthyes actinopterygii sarcopterygii calcium salts in cartilaginous endoskeleton jaws skull proto-vertebrae, true gills, two eyes, olfactory lobes many molecular characters dorsal hollow nerve cord, notochord, post-anal tail. Another type of hard tissue composed of: a matrix of (mainly) collagen fibers and other proteins. + hydroxyapatite crystals 3(ca3po4)2 . ca(oh)2 (~ 70% of the weight, rigid, hard) + water (~ 5%) produced by specialized cells called osteoblasts. Blood vessels, nerve fibers run throughout the bone in canals. Specialized cells called osteoclasts are responsible for breaking bone down. Osteoblasts then produce new bone matrix to replace the digested area (in other words, bone can repair itself). The evolution of bone: it"s older than we thought bone is found in a number of extinct fishes that existed before osteichthyes originated. This is why bone isn"t an autapomorphy for the bony fishes : [ -------- extinct jawless fishes --- ] [ -------- gnathostomata --------------- ]

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
Booster Classes
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
Booster Classes