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18 Cards in this Set
- Front
- Back
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Deuterostomia Phyla
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Hemichordata
Chordata Echinodermata - evolved from common di- or triploblastic, coelomate ancestor |
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Hemichordata: General Characteristics
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- all marine
- 2 body regions: protostome (or proboscis), collar, trunk -Coelom divided into 3 cavities -Dorsal AND ventral nerve cord, tubular in some -No major ganglia, few unspecialized sensory receptors - Pterobranchs filter feed from secreted tubes; acorn worms trap detritus with proboscis from u-shaped burrows |
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Hemichordata:
Internal Anatomy |
- Open circ system w/ dorsal & ventral blood vessels
- Blood is colorless & distributes nutrients & wastes, NOT gases (O & CO2) -Respiratory gases & metabolic wastes (NH3)) diffuse across body wall (no distinct respiratory or excretory organs) - CILIA circ water into mough and out body through pharyngeal GILL SLITS - Posses a stomochord - PHARYNGEAL GILL SLITS, STOMOCHORD, and DORSAL NERVE CORD are the advanced features of the phylum |
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Stomochord
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a semi-rigid rod-like structure below the heart
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Hemichordata:
Reproduction |
- +ly dioecious w external fertilization
- free-swimming larvae differ from adults, acorn worm larvae resemble larvae of echinoderms - Pterobranchs often form colonies by asexual budding |
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Phylum Chordata:
Distinguishing Characteristics |
-Dorsal notochord
-Dorsal tubular nerve cord -Pharyngeal gill slits -Postanal tail ALL have these traits at some point in life cycle |
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Chordata:
Notochord |
A supportive rod made of connective tissue extending the length of body, located dorsal to the body cavity
-Persists thru life in some chordates -Cartilage or bone partly or entirely replaces it in most adult vertebrates - Structure for which phylum named |
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Chordata: Dorsal Nerve Cord
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- Along longitudinal axis of body, DORSAL TO NOTOCHORD
- Usually expands anteriorly as brain |
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Chordata: Pharyngeal Gill Slits
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- Openings in pharyngeal (“throat”) region between digestive tract and outside
-In some chordates (vertebrates), do not actually connect to outside - In this case called PHARYNGEAL POUNCHES - Serve feeding (filtering) function or gas exchange in some chordates - Found in all embryos of terrestrial vertebrates, then lost |
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Chordata: Postanal Tail
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- often used in locomotion
- May be modified or reduced (e.g., human coccyx) |
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Chordata: Endostyle
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- considered a 5th Chordate characteristic by some biologists
- produces mucus to aid in digestion (mvmt of food from pharynx to esophagus) - some cells within secrete iodinated proteins similar to thyroid gland in vertebrates - ALSO, in adult lamprey, the thyroid gland arises from the endostyle - Occur in no other animal Phylum but Chordata |
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Chordata, Subphylum Urochordata:
Sea Squirts or Tunicates |
- entirely marine
- juveniles all free-swimming - some sp. colonial, some solitary |
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Urochordata:
Anatomy I |
- saclike body covered with TUNIC made of connective-like tissue
- ORAL and ATRIAL SIPHONS allow H2O circ thru body - reduced nervous system in adults w single ganglion that doesn't coordinate body fxns and no complex sensory organs - Simple heart that beats bidirectionally - hi levels of Vanadium in blood - NH3, gases exchanged by diffusion into circulating water - PYLORIC GLAND may have excretory functions |
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Urochordata:
Anatomy II |
- Have a large PHARYNX in a cavity, the ATRIUM, that circulates water
- PHARYNGEAL CILIA & STIGMAS (the remnant gill slits) enable water to circulate (for feeding & gas exchange) - Food particles (plankton & detritus) are trapped in mucus sheets secreted by the endostyle & passed to stomach - Adults lack most chordate characteristics, but all are present in the larvae |
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Urochordata:
Reproduction |
- Monoecious, w sexual repro by cross-fertilization
- brief, free-swimming larval stage - Metamorphosis into sessile adult w only pharyngeal slits - Major internal body change |
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Chordata, Subphylum Cephalochordata:
Lancelets or Amphioxus |
- all marine
- Adults eel-like; elongate, laterally compressed, nearly transparent - Mostly burrow, but can swim weakly - Filter feed |
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Cephalochordata:
Filter Feeding |
- H2o enters mouth, where CIRRI (fingerlike projections) filter large particles
- H2O & food (plankton & detritus) pass to pharynx - H2O passes out thru pharyngeal gill slits into ATRIUM (H2O-filled cavity) - H2O exits through ATRIOPORE - food trapped in mucus secreted by the ENDOSTYLE, passes thru digestive system |
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Cephalochordata:
Anatomy |
- Single photoreceptor (OCELLUS) & no brain
-Open circ system, no true heart (contractile waves in blood vessels) - Blood carries nutrients but not gasses - No respiratory organs (simple diffusion) - Adults display all 4 chordate characteristics - Dioecious with external fert'n |
