Lophophorates and Deuterosomes Flashcards
(26 cards)
What defines Lophotrochozoans as a group?
They are a clade of bilaterian animals that either have a lophophore (feeding structure of ciliated tentacles) or a trochophore larval stage.
Which phyla are included in the Lophotrochozoa?
Annelida, Mollusca, Brachiopoda, Bryozoa, and Nemertea among others.
What are lophophores used for?
They are ciliated tentacle structures used in filter feeding.
What is a trochophore larva?
A type of free-swimming planktonic larva with bands of cilia, found in annelids and molluscs.
What symmetry do adult echinoderms exhibit?
Pentaradial symmetry.
What unique vascular system do echinoderms possess?
A water vascular system, which powers tube feet for locomotion, feeding, and respiration.
What is the skeleton of echinoderms made from?
Internal calcareous ossicles (endoskeleton).
What are the major classes of echinoderms?
Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins), Holothuroidea (sea cucumbers), Crinoidea (feather stars), and Concentricycloidea (sea daisies).
How do sea cucumbers respire?
Via respiratory trees—internal branched tubes used in gas exchange.
What are Hemichordates and how are they classified?
Marine deuterostomes with features intermediate between echinoderms and chordates. Includes Enteropneusta (acorn worms) and Pterobranchia, tripartite body (proboscis, collar, trunk)
What key features do hemichordates share with chordates?
Pharyngeal slits and a dorsal nerve cord.
What is the function of the stomochord in hemichordates?
A flexible rod in the collar region once thought to be homologous to the notochord, now considered a different structure.
What are the defining features of chordates?
- Notochord, 2. Dorsal hollow nerve cord, 3. Pharyngeal slits, 4. Post-anal tail, 5. Endostyle/thyroid gland.
What are the three subphyla of Chordata?
Vertebrata, Cephalochordata (e.g. amphioxus), and Urochordata (e.g. tunicates)
Which chordate features appear in all embryos?
All five features (notochord, dorsal nerve cord, pharyngeal slits, tail, endostyle) appear in embryos of all chordates.
What is the endostyle?
A ciliated groove in the pharynx involved in filter feeding and iodine metabolism, homologous to the thyroid.
How are tunicates unique among chordates?
Their larval form shows classic chordate traits, but adults become sessile filter-feeders and lose many features.
What are key characteristics of echinoderms?
Marine deuterostomes with pentaradial symmetry, calcareous endoskeleton, water vascular system, and tube feet.
How does the water vascular system function in echinoderms?
Water enters via the madreporite, passes through canals, and powers tube feet for locomotion and feeding.
What are the two major hemichordate groups?
Enteropneusta (acorn worms) and Pterobranchia (small, colonial filter feeders).
How are hemichordates evolutionarily significant?
Share features with both echinoderms and chordates, suggesting a transitional role.
What distinguishes cephalochordates?
Retain all five chordate features throughout life; filter feeders like Branchiostoma.
What distinguishes urochordates?
Larvae have chordate features; adults are sessile filter feeders that lose notochord and tail.
What makes vertebrates unique among chordates?
Possess a vertebral column, cranium, and often paired appendages.
