Animals Lec 27-29: Mollusca, Gastropods, Echinoderms, & Chordates Flashcards
(33 cards)
Which clades and groups are the phylum Mollusca part of?
Lophotrochozoa and Protostome clade - crest and wheel animals
What are lophophores? Trochophores?
Lophophore - feeding structure, ciliated crown of tentacles around mouth
Trochophore - larval development stage. Marine, freshwater and terrestrial.
waht are shared features of molluscs?
Coelomate (non-segmented) - complete guts
3 Body regions -
Head
Ciliated or muscular foot
Visceral body region
Mantle - extension of dorsal body wall that covers visceral mass to form flaps
Radula - horny, ribbon structure in mouths of all molluscs (except bivalves)
Mucus - protects skin, anti-predator, and food capture
Explain the mollusc body plan and how it relates to the Heart, Radula, Nervous system, and metanephridium:
Heart - dorsal heart pumps circulatory fluid (haemolymph) through arteries into sinus (body space). Organs of mollusc are continually bathes in haemolymph (not in cephalopods)
Radula - mouth region in many species containing a rasp-like feeding organ. Belt of backward curved teeth repeatedly thrust outwards and retract into mouth the scrape and scoop food.
Nervous system - ring of nerves around esophagus where nerve cords extend to foot
Metanephridium - excretory organs, removes metabolic waste from haemolymph.
How do Gastropoda move?
crawling, and holding (body plan twisted). Mantle usually fully hidden in shell but the smaller the shell, the more mantle shows
How do Bivalvia move?
digging, burrowing, and crawling. Bright colors of mantle protect it from bright sunlight
How do cephalopoda move? and how do they achieve camouflage?
Cephalopoda - arms and tentacles help swim.
Mantle is all that is visible behind the head - used as jet propulsion
Outer body wall and fins are all mantle
Chromatophores in Cephalopod Mantle:
Change color, texture, and shape. - used for camouflage, defence, and communication
What are the shared features of the Echinoderms?
Deutrostome cleavage in bilateral larva
Pentamerous radial symmetry in adults (oral and aboral surfaces)
Water Vascular System (WVS) - fluid filled coelomic tubes ending in feet.
Madreporite connects WVS to outside
Endoskeleton embedded in body wall (dermis)
Excretion via tiedmanns body
Nerve ring with radial nerves
Enormous regeneration capability
summarise the characteristics of Mollusca: development, digestion, body cavities, gas excahgne, circulation, osmoregualtion, excretion, and mucus
Mollusca:
Protostomous
Coelomate
Complete gut
Gills
Open (closed for cephalopods)
Yes, they can osmoregualte
Nephridia (kidny)
If aquatic = urine is ammonia
If terrestrial = urine is uric acid
Protects skin, anti-predator, and food capture
summarise the characteristics of echinoderms including; development, body cavity, digestion, gas exchange, circulation, osmoregulation, excretion, and mucus
Echinoderms
Deuterostome
Coelomate
Complete gut
Papula
Open circulatory system
No
No excretory organ
Protects skin, anti-predator, and food capture
Major Characteristics of Chordata
- Bilateral symmetry, segmented bodies, and 3 germ layers, well developed coelom
- Notochord (skeletal rod) - cartilaginous rod, axial skeleton in chordate embryos
- Single, dorsal, tubular nerve cord
- Pharyngeal gill slits
- Post anal tail
- Segmented muscles and cartilaginous exoskeleton
- Ventral heart
- Completed digestive system
Chondrichthyes Characteristics
Cartilaginous skeleton
Lack of swim bladder
Lipid storage in liver
Unique hematopoietic organs
Actinopterygii Characteristics:
bony and rigid skeleton, not cartilage.
Many spines and ribs, complex skull of several layers.
Has a swim bladder.
Lateral lines, scales, and gills.
Briefly explain chordate phylogeny, and how agnathans and gnathostomes are rlated:
Chordate Phylogeny - deuterostomia, bilateria. Closely related to echinoderms nad hemichordates
Agnathans and Gnathostomes are common ancestors of chordates from cephalochordata with function of notochord.
Directly after vertebral column adaptations
Waht is ectothermy?
Ectothermy - an organism’s body temperature is determined by heat exchange with surroundings. Cannot produce or retain enough metabolic heat to elevate body temperature above ambient temp. Uses behavioural mechanisms instead
What is endothermy?
Endothermy - organism able to use its own metabolism as a major source of heat to maintain a greater bdoy temperature than surroundings. Allows independence from the environment and enhances physiological functions.
Explain the body plans of cyclostomes
Cyclostomes - median fins, 2 chambered hearts, simple digestive system, has sensory organs and external fertilization.
give an example of a cylcostome and one of its main processes of protection:
Hagfish - slime helps protect against predation. Slime is produced from any harm done to the surface of the fish, causing a very thick slime to form that, when in contact with water, very quickly congeals. This makes predators unable to bite down and eat hagfish
Critical innovations from superclass Gnathostomata:
- Jaws and mineralised skeletons - started as dental elements in head, then teeth, denticles, and skull. Finally skeleton of derived vertebrates
- Paired fins
- Scales and teeth
- Lateral lines - sensory system receives vibrations in water through skin pores. Canal tube under skill transmits vibrations to travel to neuromast and nerve fibers.
Waht is single circulation?
Single circulation - have a closed circulatory system with a hearth, veins, and arteries that only moves in one direction.
Explain a shark’s circulatory system steps:
Shark Circulation = sinus venosus → pericardium → atrium → ventricle → conus arteriosus → truncus arteriosus → pericardium → venal aorta
Waht is the conus arteriosus? and what does it do?
Conus Arteriosus - muscular sac with valves that direct blood flow from heart. Acts as a pump into arterial arches leading to gills
Regulates blood pressure, and elastic reservoir function helps reduce pressure fluctuations
waht makes up shark skin? And explain shark teeth:
made of pulp cavity, dentine, enamel, epidermis, and dermis, with placoid scales making up complex bony structures of teeth.
Shark teeth are homologous to dermal denticles (placoids) that are continually replaced through old teeth being shed, new teeth coming in, and developing teeth in the back
explain the origin of birds:
Theropod ancestors evolved 160 mya, Archaeopteryx is the earliest known bird. Cretaceous period show gradual loss of certain ancestral dinosaur features (e.g. teeth and clawed forelimbs)
