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Deuterostomes we havestudied

EchinodermataClass Asteroidea

Deuterostomes we willnot studyPhylum ChordataSubphylum VertebrataClass Mammalia

Other Deuterostomes

Phylum Chaetognathaarrow worms

Phylum Chordata

Phylum Hemichordataacorn worms

Phylum Chaetognatha (spined jaws)

General Characteristics

bilateral deuterostomes (only larvae give the ancestry away)

body with lateral and caudal finsgrasping spines around the mouthno circular muscleno discrete excretory, respiratory, or circulatory systemventral and dorsal gangliahermaphroditic/direct developmentall marine

Basic Body Plan (and most all of the information you need to know about Chaetognaths)

About 100 speciesstreamlined and most arefound in the plankton

Pelagic predators: feed byinjecting prey with poisons

Head with grasping spines

Trunk with lateralfins

Post anal Tail w/ fin

Zonosagitta bedotiFEEDING

Feed on other planktonespecially the abundantcopepod

Grasping Spines used to capture prey

Tetrodotoxin is the poison used to immobilize prey (It is a sodium channel blocker also used by puffer fish and the blue-ringed octopus

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Nervous System

CephalizationSensory ReceptorsLarge Cerebral GanglionTactile Receptors

Excel at detecting prey!

ReproductionHermaphroditic

Radial cleavage

Enterocoelous coelom formationDirect Development (all manner of egg deposition)Rapid development to feeding juvenile

Controversy still exists about the phylogeny of these beasts

Phylum HemichordataClass Enteropneusta:

solitaryClass Pterobranchia:

colonial

Early ancestral relationship with chordatesdorsal nerve cordpharyngeal slitsStructure that is analogous to the chordate notochord

Cephalodiscus sp. (densus?)

Basic Body Plan of Enteropneusta

3 regions

1. Proboscis: feeding and burrowing structure2. Collar3. Trunk: respiration, reproduction, digestion

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Class Enteropneusta:about 75 speciesburrowing benthic marine organisms

Some form U-shapedburrows.

Covered by a ciliated Epithelium

Not too motileFairly sessile

Feeding via mucus net

RespirationGill slits in the pharynx with vasculature from the dorsal vessel

Dioecious but can’t tell girls from boys. External fertilization

Diagnostic characteristicshollow dorsal nerve cordrigid notochordpharyngeal gill slits (pouches)post-anal tail

Subphylum Urochordatatunicates, sea-squirts, salps

Subphylum Cephalochordatabranchiostomes (Amphioxus)

Subphylum Vertebrataanimals with backbones

Phylum Chordata

Protochordates (First chordates)

Halocynthia aurentia

Defining Characteristics of Chordates

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Subphylum UrochordataClass Ascidiacea: sea-squirts tunicates, ascidianssolitary or colonial~1000 species

Class Thaliacea: planktonic~100 species

Class Larvacea: (Appendicularia) probably most primative; planktonic~70 species

Class Ascidiacea

Solitary ascidians: Benthic and marineCan be quite small or range to 60 cm

Colonial ascidians are benthic and Marine. Small (~5 mm)

Botrylloides tunicates INVASIVE SPECIES

Reminder for June Fieldtrip to SitkaJune 11-13 or 14

adult larva

Comparison of the Body Plan of the Adult and the LarvaAscidian

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METAMORPHOSIS

Tail resorptionAttachmentfilter feedingdegeneration of notocordreduction of nerve cord

The Tunic (exoskeleton)

Can be very rigid but not alwaysProtein and a special polysaccharide (tunicin)

Living Tissue: with circulating blood cells. Much of the tunic is secreted by blood cells

High concentrations of vanadium (Vd+3) Reducing power used to synthesize the tunic.

Also thought to be important for defense

Ciona savignyi Styela montereyensis

Ciona intestinalisFeeding: filter feeders; water is driven through the buccal siphon into the perforated pharynx.

Endostyle: secretesmucous net to trap food particles.

Also known to concentrate iodine

Primative Thyroidgland

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Colonial Ascidians

Colonial tunicate

Class ThaliaceaAKA Salps

free-swimming(planktonic)

Have tunic and other urochordate features

buccal and atrial siphons are opposed

Colonial during some part of their life cycle

http://www.ascidians.com/families/thaliacea/Pyrosoma_atlanticum/pyrosomaatlanticum2.htm

http://www.ascidians.com/families/thaliacea/Pyrosoma_atlanticum/pyrosomaatlanticum2.htmhttp://www.ascidians.com/families/thaliacea/Pyrosoma_atlanticum/pyrosomaatlanticum2.htm

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Aggregate salps Aggregate salps

Class Larvacea orAppendicularia

free swimming (planktonic)~70 species

Lack a urochordate-type tunic but body wall secretes a gelatinous casing. Unique to this class (gelatinous house)

Reproduce by sexual reproduction

Oikopleura

Phylum ChordataSubphylum CephalochordataClass BranchiostomaAKA Amphioxus, lancelets, the fish-like chordatesdistribution: world-wide

Branchiostoma lanceolatum

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Burrow in course sandsNear shore

Filter feeders

Lack Bones and are a delicacy in Asia (1 billion a year)

Similarities with Urochordates

Urochordates Cepalochordatesbuccal siphon mouthAtrial siphon atrioporeperforated pharynx pharyngeal gill slitslarge atrium smaller atriumendostyle ventral endostyleCiliated pharygeal bar wheel organ

Business End of Filter feeding apparatus

Primitive Pituitary Gland?

Branchiostoma lanceolatum

Circulatory system of cephalochordatesmore similar to invertebrates than to vertebrates

Not lined by an endotheliumMore like channels through connective tissue

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Homology vs. AnalogyAll of these animals have similar locomotor needs.Which are homologous and which are analogous structures

Annelid polychaete

Chordate branchiostome

Chordate vertebrate (lamprey)

Notochord Evolution

THE RADIATESPhylum: Cnidaria (3 Classes)Phylum Ctenophora

Phylum Porifera (3 Classes)

THE ACOELOMATESP Platyhelminthes (3 Classes)P. Nemertea (2 Classes)

PROTOSTOMESP. RotiferaP. GnathostomulidaP: NematodaP. PriapulidaP. GastrotrichaP. Mollusca (6 Classes)P. Annelida (3 Classes)P. Arthropoda (3 subphyla)

>10 Classes, many orders)

DEUTEROSTOMESP. BryozoaP. BrachiopodaP. PhoronidaP. ChaetognathaP. Echinodermata (5-6 Classes)P. Hemichordata (2 Classes)P. Chordata

S.P. Urochordata (3 Classes)S.P. CepahlochordataS.P. Vertebrata (8 Classes: 4 of which are FISH, 1 Amphibian, 3 “reptiles” of which 1 is Mammalia (19 orders of which 3 are taught in Marine Mammals)

Kingdom Protistaat least 5 Phyla covered