Phylum Chordata 1
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5 Characteristics of all chordates
- Dorsal hollow nerve chord
- Pharyngeal gill slits
- Post-anal tail
The difference in reproductive success of individuals based on genetic traits
Notochord characteristics (4)
- Extends the length of the body
- Axis for muscle attachment
- Allows for undulating movements
- In vertebrates, it's replaced by vertebrae
What is the flexible, rodlike structure found in all chordates?
What is the first part of the endoskeleton to appear in the embryo of all chordates?
What body part persists throughout life in protochordates and jawless vertebrates?
Dorsal Hollow Nerve Chord (3)
- Dorsal to notochord
- Hollow tube is fluid-filled
- Becomes the spinal cord in vertebrates
How is the dorsal hollow nerve chord formed?
Formed by infolding of the ectoderm
What do the pharyngeal gill slits in primitive chordates become?
What do the pharyngeal gill slits in aquatic vertebrates (fishes & sharks) become?
What 2 things do the pharyngeal gill slits in tetrapods become?
Eustachian tubes (ear structure) & other jaw structures
- Feeding structure in primitive chordates
- Cells secrete hormones
- Becomes thyroid glands in lampreys and vertebreates
What did the postanal tail provide for larval tunicates and amphioxus to swim?
The postanal tail plus musculature, provided motility
What other phylum is a sister taxa to Chordates?
Cephalochordata & Urochordata
What drives water into the mouth of a lancelet?
Water movement process of lancelets (2)
- Buccal cavity and pharynx
- Through the pharyngeal slits where food is trapped by mucus
In lancelets, what secretes the mucus that traps food?
What role do pharyngeal slits play in lancelets?
Filter feeding & gas exchange
When are the chordate characters evident in tunicates?
Characteristics of tunicate
- Loss of tail & notochord as adult
- Sessile as adult
Characteristics of Subphylum Vertebrata (3)
- Physiological upgrades
What does the endoskeleton of vertebrates consist of? (3)
- Notochord in embryonic stage
Why is the vertebrates head so important?
it holds the brain and sensory equipment
Allows for specialization
Why is olfaction important in vertebrates?
It allows animals to smell
What are some physiological "upgrades" of vertebrates? (2)
- More active as predators
Class Agnatha (2)
- Hagfish & Lampreys
- Lack jaws and paired fins
About 30 species
- Produce tons of slime
- Scavengers that feed on dead animals
What was on land before fish got there?
Plants, arthropods, and some molluscs
3 Reasons why fish moved to land
- Unlimited niches
- Lack of predators
- Lots of available resources (food)
What is a niche?
Specific role an animal plays in an ecosystem
Pros of fish moving to land (2)
- 20x more oxygen than in water
- Fewer predators
Cons of fish moving to land (2)
- Temperature fluctuations
What are the 2 major groups of vertebrates?
Agnatha (w/out jaws) & Gnathostomes (w/ jaws)
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