Origin & Architecture of Fishes Flashcards
How did the earliest ancestors of the fishes arise?
Paedomorphosis- Adult stage is progressively delayed and creature persists in the larval form
vertebrates arose from tunicate
Creatures eventually became sexually mature while still in larval form
Hence the sessile adult stage was abandoned entirely and basic body form of fishes arose
Cephalochordates
notochord
Main internal support
Cephalochordates
what is the division of nervous system?
Somatic- segmented hunk structures
Visceral- controlling soft organs
What are the two key difference between cephalochordates and vertebrates?
Cephalochordates- small with O2 requirements that diffuse across the body surface; pharyngeal perforation for feeding
Invertebrates- perforations used as gills for O2 uptake
Vertebrates- acquisition of a cartilaginous or boney vertebral column to replace the notochord varying degrees of vertebral development among fishes.
Vertebrates are split into two different vertebral developments in fishes
Lampreys & Hagfish - little traces of vertebrae
Perch like fishes- have a well developed vertebral structure
Cephalochordates notochord goes to
snouth –> 1 Hox gene cluster
Vertebrates notochord
terminates behind the skull and is more defined
4 Hox gene cluster
In the evolution of fishes what is the two events that are most noteworthy?
Acquisition of mobile paired appendages
Development of functioning jaws
Agnatha
No Jaws
Gnathostomata
Jaws
Fish- What is it?
Possess a cranium
Aquatic through life
Relies mainly on gills for gas exchange
What kind of class are
Hagfishes & Lampreys
Agnatham without jaws
Hagfish
Rudimentary eyes
Thick skin and elongated
marine predators & scavengers that lack paired fins and vertebrate
skeleton is cartilaginous
(60 species)
Lampreys
spend time buried in sediment
larger species “parasitic” feeding on marine mammals
(41 extant species )
Cartilaginous Gnathostomes have
Jaws
paired appendages
cartilage skeleton
What are the two groups of cartilaginous Gnathostomes?
Elasmobranchii
Holocephalans
Elasmobranchii have
serial gill slits along side of head*
Sharks & Rays
Holocephalans
single gill opening on each side
common name is Chimaera (mythical beast)
found in deep oceans
Bony Fishes
Most diverse taxon of fishes
Half of living vertebrates are the least understood due to deep sea.
Lungfishes given rise to the tetrapods
Coelacanths are thought to be extinct relatives
Class Actinopterygii
Ray finned
Subclasses of Actinopterygii
Chondrostei -Many fins (sturgeons, bichirs, paddlefishes)
Neopterygii- New fins (gars, bowfin & division Teleostei)
What is the class and order of the Lamprey?
Class Cephalaspidomorphi
Order Petromyzontiformes
What is the class and order of the Hagfish?
Class Myxini
Order Myxiniformes
What is the class and order of the Shark?
Class Chondrichthyes
Subclass Elasmobranchii
What is the class and order of the Ray?
Class Chondrichthyes
Subclass Elasmobranchii
What is the class and order of the Chimaera?
Class Chondrichthyes
Subclass Holocephali
Venomous barb
What is the class and order of the Teleost?
Class Actinopterygii
Subclass Neopterygii
True fishes
What is the class and order of the Lungfish?
Class Sarcopterygii
Superorder Ceratondontimorpha
Environmental constraints on the design of fishes
Denisity
Oxygen
Ions
Sensory
What are the three basic linearges
Agnaths -Jawless
Cartilaginous- sharks, skates, rays, ratfish
Boney Fishes- Grouper
FIsh mouth
inferior- stergons
subterminal-dace
terminal- trout
superior-sandfishes
Fish Barbels
fleshy elongated structures that are tactile and chemosensory receptors
Cirri
various flaps of skin on lips or other head parts
Fimbria
lampreys have these structures surrounding the mouth
Oronasal grooves & labial folds
mouth region of sharks and rays which helps maintain the flow of water through nostrils
Lateral Line sensory sytem
sensory canals on head recognized by rows of pairs or open grooves in skin
Fish nostrils
no internal openings to oral cavity except for hagfishes, lungfish, and bony fishes.
What kinds of fins to fish have
Dorsal, anal, caudal, pectoral, pelvic
Dorsal fins
Modified dorsal fins
Bichirs and lungfishes
Anal Fins
located posterior to anus
lacking anal fin fish include lamprayes chimaeras, skate, rays, some sharks, few bony fishes.
Finlets are posterior to anal fins –> tunas, macherals, allred fishes
Caudal Fins
Variety of shapes, sizes. Swimming habits may be deducted to some extort from caudal fin.
Paired Fins
Pectoral fins of bony fishes- composed of soft rays only bone by pectoral girdle.
Pelvic fins
smaller than pectoral fins, restricted in function, subject to greater variation in placement
organs in copulation (claspers)
Benthic species liek sculpins-hold them in place
algae eaters -> pelvic fins evolved into ventral sucking structures aid fish in holding onto substrate
Skin and Scales
Epidermis
Dermis
Scales
Epidermis
10-30 layers of cells
unicellular mucous glands that discharge mucus -> slimy layer (clownfish protects from anemone
photophones- deep water fish
Dermis
support for epidermis dominant feature is scales
Scales
Most fish have dermal scales
86 scales- catfish
Embedded in skin -eels
modified into bony plates or scutes
Placoid scales
Ganoid Scales
Cycloid Scales
Placiod scales
sharks -> Basal plate, containing some bone cells, buried in skin, w raised portion exposed
Ganoid Scales
Bichirs, reedfish & gars, caudal fin of sturgeons and paddlefishes.
Cycloids Scales
Scales of teleost fishes
What are the body shapes in fishes for a large round almost oval circle
Fusiform -Tuna scombridae
Body shape for a flat pancake with a lump?
Depressiform- skate Rajidae
Body shape for a oval
Compressiform- Sunfish Centrachidae
Body shapes for a perfect small circle?
Anguilliform- eel, Anguillidae
Body shape for a tiny perfect circle?
Filiform- Snipe eel, Nemichthyidae
Skinny tall oval body shape?
Taeniform- gunnel, Pholidae
Body shapes that is and flatter oval
Sagittiform- pike, Esocidae
Body type of a Big Round perfect circle?
Globiform- lumpsucker, Cyclopteridae
Caudal fin shapes
Rounded C
Truncate D
Emarginate K
Forked <
Lunate (
Living agnatha skulls
Hagfish - tectal cartilages outside of skull
Lamprey - branchial cartilages looks like a basket
What is the relationship of mandibular arch to neurocranium in three types of jaw suspension?
Neurocranium, Mandibular arch, hyoid arch
Hyostylic - hyoid arch credeling mandibular arch
Amphistylic - mandibular arch protrudes forward
Hyostylic - broken and large hyoid arch
Vertebrae of teleost fish
Abdominal- protect viscera
caudal head- head
Skeletal supports of dorsal fin Shark
Basal cartilages smoother
Skeletal Bony Fish (Teleost)
fins inside
Pterygiophores - distal middle proximal
fins outside of the body.
Fin ray
Skeletal supports of paired fins of shark
Aquatic to terrestrial environment
Pectoral- coracoid process girdle
Pelvic- propterygium ankle
Soft & Spinous Rays
Soft- lateral fanned out anterior knifelike
Spiney- lateral curved knife anterior anchored spine
