Sister group
Closest relative of another evolutionary group
Phylum Chordata
Contain all vertebrates and some invertebrates, bilaterian and deuterostomes
Chordate
Animals that at some point during development possess a notochord, dorsal, hollow nerve cord, pharyngeal slits, and muscular post anal tail
Bilaterian
Animal that has bilateral symmetry
Deuterostome
Animal that forms anus first mouth second
a vertebral column
What do invertebrate chordates lack
Derived Character
A trait that arose in the most recent common ancestor of a lineage and was passed on to all of its descendants
Notochord
dorsal hollow nerve cord
pharyngeal slits
muscular post anal tail
What are the derived characters of chordates
Notochord
Longitudinal, flexible rod made of tightly packed mesodermal cells that runs anterior-posterior axis of the dorsal part of the body, offers skeletal support
Mesodermal cells
Cells that originate from the mesoderm
Anterior
Refers to the front of the body, near the head
Posterior
Refers to the back of the body near the tail
Dorsal
Relating to the back/upper side of an animal
Dorsal hollow nerve cord
Develops from the ectoderm to form the central nervous system
Ectoderm
Outer germ layer
Pharyngeal slits/clefts
Series of arches separated by grooves that forms along the outer surface of the pharynx can later develop into slits that open into the pharynx, allows water entering the mouth to exit the body
Pharynx
Hollow area behind the mouth and nose that connects the mouth to the esophagus
Gills
Respiratory organ believed to have evolved from pharyngeal slits
Muscular, post-anal tail
Helps to propel many aquatic species, contains skeletal and muscular elements; greatly reduced in many species
Phylum Cephalochordata
Contains lancelets, invertebrate chordates; sister group to all living chordates, often used for showing derived characteristics of vertebrates
Invertebrate chordate
Chordates that lack a vertebrae
Phylum Urochordata
Contains tunicates (sea squirts), sessile marine invertebrate chordates; more closely related to other chordates than lancelets
Hox genes
Genes that regulate body plants in animals
Italicized
How do you write genes
Normal
How do you write products of genes (ex. proteins)
Vertebrate
A chordate with a backbone
2 or more sets of Hox genes and a neural crest
What are the derived characters of vertebrates
Neural crest
Collection of cells that appears along the edges of the closing neural tube of an embryo
Phylum Myxini
Contains hagfishes, marine jawless with rudimentary vertebrae; produce slime to escape predators
Rudimentary vertebrae
Backbone made of cartilage instead of bone
Clade Cyclostoma
Living jawless vertebrates; hagfishes and lampreys
Slime
Sticky substance produced by hagfishes as defense, clogs gills of predators
Phylum Petromyzontida
Contains lampreys, marine or freshwater and can be parasitic; jawless with rudimentary vertebrae
Inset
Mouth of parasitic lampreys
Clade Gnathostoma
Living jawed vertebrates, includes every other vertebrate chordate besides lampreys and hagfish
They have derived characteristic of chordates yet lack a backbone they instead possess a notochord
Why are all chordates not vertebrates
They have a rudimentary backbone made of cartilage and possess all the other derived characters of vertebrates
How are lampreys and hagfishes grouped under vertebrates if they don't have a backbone?