BIO2231 Lecture Notes - Lecture 17: Amniote, Undulatory Locomotion, External Fertilization
30 May 2018
School
Department
Course
Professor
Phylum Chordata
• Bilateral, deuterostome, coelomates
• Five major features; 1. Notochord; flexible rod of fluid filled with cells surrounded by a tough
sheath, not same as spine, hyrdrostatic, high pressure
2. Dorsal tubular nerve cord; tube shaped, front usually enlarges to form
brain, epyndermal cell, cerebral fluid
3. Pharyngial pouches/slits; for filter feeding, water through pharynx into
digestive system, squirt water through slits
4. Endostyle (thyroid gland); ucous to trap food, e do’t hae edostyle
- for filter feeding, iodinated proteins
- found in all chordates
5. Postanal tail; locomotory, swimming, usually supported by notochord
• Coelom surrounded by mesothelium (mesoderm)
• dorsal tubular nerve cord is formed by endodermal tissues during embryological development
Subphylum Cephalochordata
• Lancelets
• Bottom dweller, filter feeder (atrium with atriopore; where water leaves, slits are for feeding not
gills)
• Marine, fish like
• Has notochord and endostyle
• Metameric segmentation
• Nephridia
• Model chordate
• Lack vertbrae
• Myomere of muscles
• Atrium third cavity
• NS; ocellus
• Sexes separate
• Planktotrophic larva
• Maintains dorsal tube system without brain
Subphylum Chephalochordata
-Lancelets
-filter feeder
-dorsal and ventral vessels but
no true heart
-buccal cavity is surrounded by
cirri and contains velum and
wheel organ
Branchiostoma (Amphioxus)
find more resources at oneclass.com
find more resources at oneclass.com
Subphylum Urchordata (Tunicata)
• Marine
• Larval form displays chordate hallmarks, free swimming, notochord restricted to tail region
• Adults usually sessile
• Tunic; hard leathery material (tunitin)
• Metamorphosis; lose notochord and tail, dorsal nerve cord reduced
• Incurrent and excurrent openings (siphons)
• Closely related to vertebrates
• Perforated pharynx and endostyle form elaborate filter feeding organ
• Outer coat of secreted material covers body
• Class Ascidiacea (sea squirts)
• Class Appendicularia/Larvacea
• Class Thaliacea (salps)
• Look like rocks
Class Thaliacea
-salps
-pelagic, planktonic
-free swimming
-single or colonial
-incurrent (buccal) and
excurrent (atrial) on opposite
sides
-water current for feeding,
respiration and locomotion
-compress liquid in atrium for
propulsion
-often translucent
Salpa
Class Ascidiacea
-sea squirts
-marine
-mostly sessile
-atrial cavity receives water
from gill slits and discharges
through atrial pore
-2 siphons
-pharyngeal slits, endostyle
-parallel circulation
-hermaphrodite
-solitary, colonial, compound
Class Larvacea
-pelagic
-marine, planktonic
-adults neotenic
-larva like
-paedomorphic
-feeding house (dispose when
clogged up with food), builds
house very fast, has incurrent
Oikopleura
find more resources at oneclass.com
find more resources at oneclass.com
and outcurrent orifices and
captures food in net
Subphylum Craniata (vertebrata)
• Have 5 hallmarks
• Cranium; derived from neural crest cells, brain, highly developed
• Cartilage or bone endoskeleton
• Tripartite brain, cranial nerves, paired sense organs
• Integument; epidermis + dermis
• Muscular pharynx and digestive tract, liver, pancreas (liver and pancreas not seen in other
groups)
• Circulation with ventral heart
• Endocrine system
• Paired glomerula kidneys
• Musculoskeletal modification; endoskeleton, vertebra + neural spines (small blocks of cartilage
that form around notochord as ring, notochord completely disappeared in humans)
• Physiology upgrade; heart and circulation, kidneys, muscular pharynx, digestive glands
• Ectodermal cells derived from neural crest migrate throughout body
• Placode; sensory, olfactory etc
• Free swimming chordate ancestor, not sessile
• Early vertebrates; ostracoderm; heavily armoured, jawless, one of oldest, very heavy
-filter feeding, pectoral fins
-placoderm; all had pectoral and pelvic fins, also very slow (all extinct)
-armoured, jawed
• Origin of jaws in vertebrates; first/second gill arches (cartilage), from neural crest
-from pharyngeal pouches/gill arches
• Agnatha (jawless); Class Myxini (hagfishes)
-Class Petromyzontida (lampreys)
• Gnathostomes (jaw); Class Chondricthyes (sharks, skates, rays)
- Class Actinopterygii (ray-finned fishes)
- Class Sarcopterygii (lobe-finned fishes)
• Earliest vertebrates are most likely related to modern agnatha; skull but no jaws, modern are
often parasitic, feed on other fish by boring hole through skin and eating victim from inside out
• Osteichytes (bony fishes); Actinopterygii and Sarcopterygii
endochondral bone, paired fins (more mobile), operculum (single
gill opening, lung/swim bladder from gut), can ventilate
-more than half vertebrates are teleosts
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Phylum chordata: bilateral, deuterostome, coelomates, five major features; 1. Notochord; flexible rod of fluid filled with cells surrounded by a tough sheath, not same as spine, hyrdrostatic, high pressure. Dorsal tubular nerve cord; tube shaped, front usually enlarges to form brain, epyndermal cell, cerebral fluid. Pharyngial pouches/slits; for filter feeding, water through pharynx into digestive system, squirt water through slits. Endostyle (thyroid gland); (cid:373)ucous to trap food, (cid:449)e do(cid:374)"t ha(cid:448)e e(cid:374)dostyle. Postanal tail; locomotory, swimming, usually supported by notochord: coelom surrounded by mesothelium (mesoderm, dorsal tubular nerve cord is formed by endodermal tissues during embryological development. Lancelets: bottom dweller, filter feeder (atrium with atriopore; where water leaves, slits are for feeding not gills) Lack vertbrae: marine, fish like, has notochord and endostyle, metameric segmentation, nephridia, model chordate, myomere of muscles, atrium third cavity, ns; ocellus, sexes separate, planktotrophic larva, maintains dorsal tube system without brain. Dorsal and ventral vessels but no true heart.
