At what time did invertebrate animals inhabit Earths ocean
Cambrien period aprox 530 million years ago
when did one lineage of vertebrates colonize land
- 365 million years ago
- They gave rise to modern amphibians, reptiles (including birds), and mammals
The phylum Chordata .... are______ animals that belong to the clade of animals known as _________
two groups of invertebrates : the urochordates and cephalochordates
Four key characters of chordates
- Dorsal, hollow nerve cord
- Pharyngeal slits or clefts
- Muscular, post-anal tail
- is a longitudinal, flexible rod between the digestive tube and nerve cord
- It provides skeletal support throughout most of the length of a chordate
A. Dorsal hollow nerve core
D. Neutral Crest
- The nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
- The nerve cord develops into the central nervous system: the brain and the spinal cord
A. Dorsal hollow nerve core
B. Neural tube
D. Neutral Crest
Pharyngeal slits are ...
- In all chordate embryos, grooves form along the outer surface of the pharynx called pharyngeal clefts
- In most chordates, these grooves develop into pharyngeal slits that open to the outside of the body
Functions of pharyngeal slits
1.Suspension-feeding structures in many invertebrate chordates
2.Gas exchange in vertebrates (except vertebrates with limbs, the tetrapods)
3.Develop into parts of the ear, head, and neck in tetrapods
Muscular post anal tail describe
- Chordates have a tail posterior to the anus
- In many species, the tail is greatly reduced during embryonic development
- The tail contains skeletal elements and muscles
It provides propelling force in many aquatic species
- They are marine suspension feeders that retain characteristics of the chordate body plan as adults
Urochordata = Tunicates
More closely related to lancelts or chordates
when do they most resemble chordates .... what is unique about this stage
- Tunicates (Urochordata) are more closely related to other chordates than are lancelets
- Tunicates most resemble chordates during their larval stage, which may last only a few minutes
What do Tunicates do when attacked
- "sea squirts" (in-current siphon)
Unique features of Tunicates ....
- Metamorphosis from the larva to adult form involves the resorption of the tail and notochord and 90° rotation of the remaining organs
- Adult tunicates draw in water through an incurrent siphon, filtering food particles
- Tunicates are highly derived and have fewer Hox genes than other vertebrates
A skeletal system and complex nervous system have allowed vertebrates efficiency at two essential tasks:
- Capturing food
- Evading predators
Derived Characters of Vertebrates
- two or more sets of Hox genes
- the vertebrae that enclose the spinal cord have taken over the mechanical roles of the notochord
- The neural crest, transitory cells that appear along the edges of the closing neural tube of an embryo
Cyclostomes: Hagfishes and Lampreys
Gnathostomes are ...
Vertebrates with jaws make up a much larger clade, the
- cartilaginous skull, reduced vertebrae, and a flexible rod of cartilage derived from the notochord
- They have a small brain, eyes, ears, a nasal opening, and tooth-like formations in their mouths
- All hagfishes are marine; most are bottom-dwelling scavengers
- Hagfishes produce slime to repel competitors and predators
Petromyzontida = Lampreys
- Lampreys are jawless vertebrates that inhabit various marine and freshwater habitats
- Some are parasites that feed by clamping their mouths onto a live fish
- Free-living species feed as larvae for several years and then mature, reproduce, and die within a few days
- Lampreys have a notochord and cartilaginous skeleton
Fossils from the Cambrian explosion document the transition to...
- The most primitive of the
fossils are those of the
- Haikouella resembled lancelets but had a well-formed brain, eyes, and muscular segments but lacked a skull and ear organs
is considered the first vertebrate to have a head (brain, eyes, skull – even though the skull was “partial”). It still lacked vertebrae.
- were among the earliest vertebrates in the fossil record, dating to 500 million years ago
- They had a set of barbed hooks at the anterior end of the mouth used for capturing prey
- These hooks, and another set of dental elements in the pharynx, were mineralized
Which clade does not include humans?
Animals that are classified as vertebrates and have rudimentary vertebrae are the ______ and the ______.
Which of the following is a tetrapod? select all that apply :
mammal bird amphibian reptile
Which evidence supports the hypothesis that four-limbed animals came from fish? Select all that apply.
Both fish and four-limbed animals are vertebrates.
DNA analysis shows that fish are tetrapods’ closest relatives.
Fish and four-limbed animals have very similar embryos.
Fossil evidence shows there have always been four-limbed animals on Earth.
The fossil record shows more and more tetrapod-like fish before the appearance of tetrapods about 365 million years ago.
all except the fossil evidence shows there has always been...