Ch 34 - Chordates

Describe the characteristic derived traits of mammals

-Mammary glands that produce milk. -Hair and insulating layer of fat beneath skin. -Diaphragm to help ventilate the lungs. -Generally larger brain than other vertebrates of equivalent size. -Extended care period for the young. -Differentiation of teeth.

Describe the four derived traits that define the phylum Chordata

-The notochord is a longitudinal, flexible road located between dorsal cord and the digestive tube. Notochord provides skeleton support. In most vertebrates, more complex skeleton developed around the ancestral notochord. -Dorsal, hollow nerve cord developed from a plate of ectoderm. This nerve cord is only unique to chordates. This chords later developed to the central nervous system : the brain and spinal cord. -Pharyngeal clefts( or slits ) function as digestive tuebe that extends from mouth to the anus. It allows water to enter the body and leave the body without passing through entire digestive system. In vertebrates ( with the exception of tetrapods ), these tube have been modified for gas exchange. -Chordates' tail extends to anus, and contains skeletal elements and muscles. It later developed as the propeller of many aquatic species, although these tails are reduced during embryonic development for most of animals.

Describe conodonts, and explain why they are considered vertebrates

1. "Cone teeth" 2. They were the first to have mineralized skeletal elements in mouth and pharynx 3. Considered vertebrates b/c of this. 4. The fully mineralized skeleton came later

Name the three living lineages of lobe-fins

1. Coelecanthes (Actinista) 2. Lungfishes (Dipnoi) 3. Tetrapods

Describe the way of life and unique characteristics of the lamprey

1. Petromyzontida 2. JAWLESS 3. Adults in Saltwater 4. Cartilage surrounds the notochord in lampreys 5. Marine and aquatic

List the modification of birds that are adaptive for flight

Adaptations to reduce weight: no urinary bladder, females have 1 ovary, males and femals have small gonads, light skull and no teeth. Most obvious adaptations for flight are the wings and feathers.

Explain why non-bird reptiles should be called "ectothermic" rather than, "cold-blooded"

Because their blood isn't cold; rather they must obtain energy from the environment around them - such as heat from the sun

Explain why the reptile clade includes birds

Birds lay their eggs on land just like the rest of the clade

Describe and distinguish between Chondrichthyes and Osteichthyes, noting the main traits of each group

Chondrichthyes i. All Cartilage ii. Oil in liver for buoyancy iii. Carnivores iv. Lateral line system sense electricity as well as vibrations Osteichthyes i. Bone skeleton ii. Covered in scales iii. Secrete slime to cover body and reduce drag iv. Operculum = Flap over gills v. Swim bladder vi. Not all are carnivorous vii. Use lateral line system to sense vibrations

Describe the evidence that suggests that the loss of bone in Chondrichthyes is a derived feature

Chondrichthyes are sharks rawr -- something else exciting is that they have an adaptive immune system (1) presence of mineralized skeleton in earlier animals like Conodonts suggests that sharks lost bone after they diverged from gnathostomes (2) most shark species have some calcium in their skeleton (3) traces of bone found in scales, base of teeth, and on vertebrae surface (4) bonelike tissues found in some early shark fossils

Describe the common traits of amphibians and distinguish among the three orders of living amphibians

Common Traits i. All are tied to water ii. 3 chambered heart iii. Larvae are aquatic iv. Adults are terrestrial v. Breathe through skin vi. Hear through tympanum vii. External fertilization viii. Eggs to not have shell Three Orders of Living Amphibians i. Urodela 1. With a TAIL 2. 550 species 3. Retail larval traits as adults ii. Anura 1. WithOUT a TAIL 2. 5,420 species 3. Frogs / toads 4. May secrete toxic slime on skin 5. Breathe by positive pressure iii. Apoda 1. Without LEGS 2. NOT SNAKES 3. 170 species 4. Larvae feed on plankton 5. Reduced eyes 6. Carnivores 7. Mouth lined with teeth

Define and distinguish between gnathostomes, tetrapods and amniotes

Gnathostomes i. JAWED ii. Lateral line system to sense vibrations iii. Enhanced smell and vision (enlarged forebrain) Tetrapods i. 4 feet ii. can detect sounds in AIR iii. 2nd vertebrae in neck for side-to-side as well as up-and-down movement iv. bones of pelvic girdle are fused to backbone v. Pharyngeal clefts develop into ears, glands, etc. Amniotes i. Produce and amniotic egg ii. Membrane protects embryo iii. Relatively impermeable skin iv. Ribcage - breathe by negative pressure

Explain the significance of Archaeopoteryx

It has teeth and tail like reptiles and wings like birds. So, it serves as a connecting link between the reptiles and birds. It shows that birds have evolved from reptiles.

List the shared, derived characters that characterized gnathostomes

Jaws Additional duplex of Hox genes Lateral Line System

Explain the fate of the neural crest cells in craniate development

Neural crest gives rise to organs such as skull, brain, eyes and other sensory organs

Distinguish among monotereme, marsupial, and eutherian mammals

Monoterem Includes the platypus and spiny anteater. Lay leathery eggs. Nourish young with milk, but no nipples. Marsupial Includes opossums, kangaroos, koalas. Young are born very early in development and crawl to marsupium (pouch). Development is completed within the pouch. Eutherian Placental Mammals Have a longer period of pregnancy. Complete embryonic development within a uterus, joined to the mothe by a placenta.

Describe the specialized adaptations of snakes that make them successful predators

Snakes are sensitive to vibrations and temperature, unique characteristics that allow them to prey more easily

Distinguish among the three subphyla of the phylum Chordata and give examples of each

The phylum Chordata is consist of the three subphyla - the Craniata, Tunicata and Cephalochordata. The Cephalochordata has blade-like shape, and has the charateristics of Chordates. An example of Cephalochordata is a lancelet, which has pharyngeal slits, notochord, tail and dorsal nerve cord. The Urochordata resembles other chordates more than lancelets. These characteristics are most evident during larval stage. The tunicates, a common Urochordata, lose these characteristics as it becomes an adult. This metamorphosis occurred only after the tunicate lineage broke off from other chordates. Their difference can be found in the genes. Tunicates have 9 Hox genes while the chordates have 13 Hox genes. The Craniatas are the chordates that have a head. It possesses two Hox genes, compared to single Hox gene of chordates. It also has the neural crest , which is a collection of cells that appears near the dorsal margins of the closing neural tube in an embryo. Example of Craniates Myllokunmingia. Myllokunmingia had ear and eye capsules.

Distinguish between the phyla of deuterostomes

Two different subgroups of deuterostomes include chordates and echinoderm. Chordates, the ancestor of vertebrates, are made up of 4 unique parts - notochord, pharyngeal slits, muscular, post-anal tail and dorsal, hollow nerve cord. On other hand, echinoderm lacks these parts of chordates and is classified as an invertebrate. However, they both share common characteristic, such as development of anus opening prior to development of a mouth.

Describe the amniotic egg and explain its significance in the evolution of reptiles and mammals

a. Amniotic egg is i. An egg which contains a membrane that protects the embryo ii. extramembrane sac contains yolk sac, amnion, chorion and allantois b. Embryos are more protected c. Embryo has better chance at survival - is encased with food source from mother

Identify and describe the main subgroups of Osteichthyes

a. Actinopterygii i. Ray-finned fishes ii. Fins supported by long, flexible "rays" iii. Great for defense and maneuvering b. Sarcopterygii i. Lobe-finned fishes ii. Muscular pelvic and pectoral fins supported by rod shaped bones iii. 3 lineages survive today: 1. Coelecanthes (Actinista) 2. Lungfishes (Dipnoi) 3. Tetrapods

Describe the features of sharks that are adaptive for their active, predatory lifestyle

a. All Cartilage b. Store oil in liver to help control buoyancy c. Lateral line senses vibrations AND Electrical impulses d. Short digestive tract w/spiral valve to increase surface area e. Acute vision f. Amazing smell g. Mostly carnivorous

Describe the ancestral and derived features of hagfish

a. Ancestral hagfish were the first Craniates, called Mixini i. Eel like bodies ii. No bones or teeth iii. Cartilaginous skull b. Agathans = No Jaws i. Craniates without jaws c. They have a unique way of self defense - they produce a slime which suffocates their attacker by gunking up the gills.

Describe the trends in mineralized structures in early vertebrates

a. Conodonts i. "Cone Teeth" ii. First to have mineralized skeletal elements b. Pteraspis i. Armored ii. Jawless iii. Have defensive bony plates in their skin

Describe a number reptile features that are adaptive for life on land

a. Scales made of keratin for protection and waterproofing b. Internal fertilization c. Amniotic egg with outer shell d. Ectotherms

Explain one hypothesis for the evolution of the jaws in gnathostomes

evolved by modification ofthe skeletal rods that had previously supported the anterior pharyngeal (gill) slits

Describe the structure and way of life of larval and adult lancelets and tunicates

i. Adult: 1. Blade like structure 2. Marine filter feeders through pharyngeal slits 3. Breathe by gas diffusion through skin 4. Mucous in gills ii. Larval: 1. No change from adults - Adults retain the larval traits