Lecture 22 Deuterostomes Flashcards
Two phyla of Deuterostomia are
-Echinodermata
-Chordata
Echinodermata of Deuterostomia include (5)
-Asteroidea
-Echinoidea
-Ophiuroidea
-Crinoidea
-Holothuroidea
Chordata of Deuterostomia include (3)
-Vertebrata
-Cephalochordata
-Urochordata
What constitutes a Deuterostome (4)
-bilateral symmetry
-coelom (abdominal cavity) derived from mesodermal (embryonic tissue)
-radial cleavage during embryonic development
-blastopore (anus)
Echinodermata are
Mostly sessile marine animals
The sea urchin genome
Has 7000 genes in common with humans (ie. Shares a common ancestor with humans)
Echinodermata have (3)
-endoskeleton of interlocking calcium carbonate plates and spines
-water vascular system
-sexual and asexual reproduction
The endoskeleton of Echinodermata are (3)
-tightly fused in sea urchins
-loosely joined in starfish
-microscopic in sea cucumbers
The water vascular system in Echinodermata is
A network of water-filled canals that branch to form tube feet
What system provides locomotion and feeding in Echinodermata
Water vascular system
Reproduction in Echinodermata can be
-sexual (release gametes into water to spawn)
-asexual (autotomy, shed arm/comet to form new individual)
Five classes of Echinodermata are
-Ophiuroidea (brittle stars)
-Crinoidea (sea lilies and feather stars)
-Holothuroidea (sea cucumbers)
-Asteroidea (starfish and sea daises)
-Echinoidea (sea urchins)
An important aquaculture species is
Sea cucumbers (Holothuroidea)
Chordata includes three subphyla
-Vertebrata (fish, amphibians, reptiles, birds, and mammals)
-Cephalochordata (Amphioxus species)
-Urochordata (sea squirts)
Earliest chordate fossils appeared in
The Cambrian Period (~530 million years ago)
Four common features of Chordata
-notochord
-pharyngeal slits
-dorsal, hollow nerve cord
-muscular, post-anal tail
The notochord of Chordata is (5)
-a thin, elastic-like rod consisting of a core of cells and fluid surrounded by a fibrous sheath
-develops from mesoderm
-allows locomotion through lateral undulations
-lies dorsal to the coelom (body cavity)
-beneath and parallel to CNS
Coelom is the
Body cavity
The notochord in bony fish and terrestrial vertebrates is (3)
-present during embryonic development
-replaced by the vertebral column
-persists as the nucleus purposes of intervertebral discs
Pharyngeal slits are (3)
-longitudinal series of openings in the walls of the pharynx
-involved in feeding in primitive chordates (Amphioxus)
-lost during embryogenesis in terrestrial vertebrates
In aquatic vertebrates, pharyngeal slits
Are slits that allow for the flow of water across the gills (gills develop adjacent to pharyngeal slits)
The dorsal, hollow nerve cord of Chordata is (3)
-derived from the ectoderm
-lies above the gut
-is hollow and surrounds the fluid-filled neurocoel (cerebral spinal fluid)
The muscular, post-anal tail in Chordata is (2)
-a posterior elongation of the body
-made of muscle segments and extends past the anus
____ resembles the earliest chordates
Cephalochordata
Branchiostoma - amphioxus is (4)
-in the subphylum Cephalochordata, Chordata, Deuterostomia
-possess all 4 chordate features
-posterior end is buried in sand
-anterior end is exposed to water currents
The digestive system of Cephalochordata (2)
-precursor of vertebrate organs
-contains a midgut caecum which houses the liver and pancreas
The circulatory system of Cephalochordata (4)
same general pattern of vertebrates:
-ventral and dorsal aorta
-afferent and efferent vessels
-capillary network
BUT NO HEART
Cephalochordata do not have (2)
-a heart
-a differentiated brain
Urochordata includes
-tunicates (Ascidiacea - sea squirts)
All species of Urochordata are
Marine
Ascidians (sea squirts) are ___ as adults and ___ as larvae
Sessile; planktonic
Tunicates (Ascidiacea) display
All four chordate characteristics ONLY as larvae
The central nervous system of Urochordata has 3 divisions:
-Sensory Vesicle
-Visceral Ganglion
-Hollow Nerve Cord
Neural crest cells in Urochordata
Differentiate into different cell types including pigment cells
Urochordata have a ___ heart
Rudimentary
Amboebocytes in Urochordata
Resemble lymphocytes
Most basal craniates are
The Hagfishes
From the chordates evolved ____
Craniates
Craniates are
Chordates with a head (cranium)
A unique characteristic of Craniata is
Neural crest
Hagfishes, Craniata (6)
-cartilaginous skull
-lack jaws and vertebrae
-retain notochord in adulthood
-30 species, all marine
-feed on detritus
-produce mucous as defense
Craniates gave rise to
Vertebrates
Most basal vertebrates are the
Lampreys
Lampreys (Vertebrata) (6)
-cartilaginous skeleton
-lack jaws
-have a rasping tongue and teeth
-retain notochord in adulthood
-primitive vertebrae enclose notochord
-35 species, marine and freshwater
Gnathostomes transitioned from (2)
-suspension feeding to selective feeding
-paired pectoral and pelvic fins
Two lines of evolution from Gnathostomes include
-Chondrichthyes (cartilaginous fish)
-Osteichthyes (bony fish)
Chondrichthyes are (4)
-cartilaginous fish (sharks, rays, etc)
-about 700 species
-lack a swim bladder
-have placoid scales
Placoid scales in Chondrichthyes (3)
-made of dentin and enamel
-develop in dermis
-project through epidermis
Reproduction of Chondrichthyes is (2)
-internal (males have a clasper on pelvic fin)
-oviparous and viviparous
Osteichthyes are
Bony fishes
The scales of bony fishes (Osteichythyes)
Develop in the dermis and do not penetrate the epidermis
Bony fishes (Osteichthyes) can be subdivided into
-Actinopterygii (ray-finned fishes)
-Sarcopterygii (lobe-finned fishes)
Buoyancy in Osteichthyes (bony fishes) is controlled by
A swim bladder
Bony fishes (Osteichthyes) reproduce through
External fertilization
Actinopterygii of the Osteichthyes can be divided into
-Neopterygii (teleosts)
-Palaeonisciformes (Sturgeons)
Actinopterygii (ray finned fishes)
-appeared ~225mya in late Triassic
-fins supported by numerous endoskeletal rays
Teleosts are in the class
Neopterygii < Actinopterygii < Osteichthyes < Gnathostomes
Sturgeons are (5)
-the largest species of freshwater fish
-some can migrate between freshwater and marine
-toothless
-live to ~100 years
-sexually mature at ~20 years
Sturgeons are in the group
Palaeonisciformes < Actinopterygii < Osteichthyes < Gnathostomes
Lungfishes are in the group
Sarcopterygii < Osteichythyes < Gnathostomes
Sarcopterygii includes (2)
-lungfishes
-coelacanth
The tetrapod limb evolved from the
Sarcopterygii fin (fleshy fin composed of soft muscles)
Three genera of lungfishes
-Neoceratodus (QLD)
-Proptopterus (Africa)
-Lepidosiren (South America)
Lungfishes (Sarcopterygii) (2)
-can breathe air when O2 levels in water fall or when pools dry out
-have a notochord
Coelacanth are in the group
Sarcopterygii < Osteichythyes < Gnathostomes
Coelacanth were thought to
Have become extinct 75 Mya
Coelacanth possess (4)
-tiny vertebrae
-well developed notochord
-a swim bladder filled with fat (does not serve in respiration)
-lobe fins used to support and position
