Lecture 8 RH - Fishes Flashcards
How is the nerve chord arranged in subphylum vertebra?
Hollow dorsal nerve chord extended anteriorly into the brain
What protects the brain in subphylum vertebra?
The cranium
What is the variation of notochord destination in subphylum vertebrata?
Basal clades’ notochord terminates at cranium
Advanced clades’ notochord is replaced by cartilaginous or bony vertebral column
What are the anatomical features of subphylum vertebrata?
Head, trunk, and post-anal tail
No atrium
Well developed ventral heart
What are pharyngeal clefts and what happens to them in subphylum vertebrata?
Gill slits
They can only be seen during embryonic stages of development.
What is the destination of the notochord in vertebrates?
vertebral column
What does the nerve chord connect to directly?
The brain
What did limbs rise from?
paired fins
Where did lungs arise from?
gills
What is a fish by definition?
Aquatic vertebrate with gills.
All vertebrates that are not tetrapods
Appendages if present in the form of fins
Scaly skin
How many extant species of fish are expected to exist?
~28k species
What is the most diverse vertebrate grouping?
Fish
What is the dominant animal type in aquatic environments today?
Fish
Which fish group did tetrapods arise from?
Sarcopterygians
Where did fish come from?
Unknown free-swimming protochords
Earliest “fish-like” vertebrates were a paraphyletic assemblage of jawless agnathan
What are the anatomical features of agnatha?
Cylindrical body
Cartilaginous skeleton
Heterocercal tail (Not symmetrical)
No paired fins. Fins have a broad base
What are agnatha? Examples
Jawless fishes such as lamprey and hagfish
What is the class that hagfishes are a part of?
Class myxini
Where do hagfishes typically live?
Marine entirely
What do hagfish feed on?
Dead or dying fishes and marine invertebrates.
Scavengers and predators and feed on whale carcasses
How do hagfishes attach to food?
keratinized plates and rasps off tissue with tongue
Ties a knot for extra leverage
How do hagfishes maintain osmotic concentration in marine water?
Body fluid concentration maintained in osmotic balance with seawater
What do hagfishes feel like?
Very slimy
How do hagfishes reproduce?
Large eggs that don’t hatch larvae
Why do hagfish tie themselves into a knot when hanging onto prey?
To maintain leverage
What class are lampreys?
Petromyzontida
Where do lampreys typically live?
Marine and freshwater forms
All species spawn in freshwater streams
Ammocoeote larva burrows in mud for 3-7 years
How do parasitic lampreys attach to other fish?
using sucker-like mouth
How do non-parasitic lampreys eat?
They don’t eat after emerging as adults from the mud and spawn before dying.
What is the most diverse group of vertebrates?
Jawed fishes
What are the 2 classes of jawed fishes?
Chondrichtyes (cartilaginous fishes)
Osteichthyes (bony fishes)
What are the types of Chondrichtyes?
Elasmobranchs: Skates, rays, and sharks
Holocephali: Chimaeras (ratfishes)
What are the features of chondrichthyes?
Most are marine predators
Flexible cartilaginous skeleton
Paired fins
Placoid scales
Special electrosensory organs on dorsal part of head and lateral line system
Do chondrichthyes have an operculum?
No
How do skates and rays adapt to having no operculum and living on the sea bed?
Large spiracles prevent clogging of gills
Why was Steve Irwin’s death possible?
Stingrays have saw-toothed spines on their whip-like tail
How do electric rays electrocute people?
Electric organs on the side of their head
What is the nutrition habits of sharks?
They are predators
Where does the vertebral column end in sharks?
Asymmetrical heterocercal tail-vertebral column turns upwards and extends into dorsal lobe of tail
What is interesting about shark teeth?
Replaceable very easily
What are chimaeras?
Fish that have no teeth and instead have jaws with flat plates connected to them
How are the stomach an intestine related in ratfish (holocephali)?
Stomach infused with their intestine
What is holocephali spines like in appearance?
Erectile, dorsal spine, it is sometimes poisonous
What are osteichthyes?
Bony fish
What are the 2 classes of Osteichthyes?
Sarcopterygii
Actinopterygii
What are the features of osteichthyes?
Skeleton is hardened with calcium salts = bronyl
Sim bladder present for buoyancy. Often associated with digestive system and used for oxygen uptake
Do osteichythyes have an operculum?
Yes
How can sarcopterygii and actinopterygii be differentiated from each other?
sarcopterygii have very strong muscular, lobe like fins
How many extant species of sarcopterygii are there?
8 extant
Which species of sarcopterygii gave rise to tetrapods?
Rhipidistians
Can Australian lungfish survive outside of the water?
Not for long
Can protopterus (African) and Lepidosiren (South American) lungfish survive outside of the water?
They can survive for longer than Australian (Neoceratodus) lungfish.
Are lungfish related to tetrapods?
Yes they are the closest living relatives to tetrapods but not direct ancestors
Which lungfish are from Australia?
Neoceratodus
Which lungfish are from Africa?
Protopterus
Which lungfish are from South America?
Lepidosiren
What are the subclasses of class actinopterygii?
Chondrostei (cartilaginous, non-teleost) such as sturgeons
Neopterygii (bony, non-teleost and teleost fishes)
Which fish are the ray-finned fishes?
Actinopterygii
Where is the swim bladder located relative to the digestive system?
dorsal
Where are the kidneys located relative to the digestive system?
dorsal
What are the components of the tail?
Area right before the caudal fin is known as the peduncle and is narrow and stiff which ends into a sickle shaped caudal fin.
What is the function of myomeres?
Important for locomotion
How do fish generally move?
tail pushes against water and reactive force pushes it forward.
*Eel loses force due to lateral movement
What are the components of the scales of a fish?
Bony part
Mucous gland covers bony part
Epidermis covers mucous glands
Dermis is deep to all other structures
What are the scale types seen in fishes?
Placoid scales in cartilaginous fishes. very similar to teeth
Genoid scales (diamond shaped) in non-teleost bony fishes
Cycloid scales (very circular and uniform) and ctenoid scales in teleost fish
What is the function of the swim bladder?
It is a large liver with lipid squalene which has a low density (0.86) this is important to prevent sinking when not swimming
Do sharks have a swim bladder?
No
What is the consequence of lacking a swim bladder?
Movement is more dependent on heterocercal tail and movement needs to be maintained in order to prevent sinking
What are the variations in swim bladder arrangement?
Bony fish have gas filled swim bladder
Pelagic fish have one but tuna, abyssal fish, and bottom dwellers lack a swim bladder
How do teleosts maintain the amount of air in the swim bladder?
pneumatic duct connects swim bladder with oesophagus
In more advanced teleosts there is no duct and air is exchanged with gases in blood. As a result it is highly vascularized and gas is secreted into bladder via gas gland.
Gas gland makes blood more acidic via lactic acid
What are the sheets of filaments of the gills called?
lamellae
What type of regulators are freshwater fish?
hyperosmotic regulators
How do freshwater fish regulate their internal osmolarity?
They don’t drink water
They produce dilute urine
They prevent water uptake and salt loss
Epithelium of gill contains salt absorbing cells
How do marine fish regulate their internal environment?
Hypoosmotic
Salt secreting cells in the gills (chloride cells)
Salt also voided in faeces
Drink seawater
What does catadramous mean?
Fish that spend the majority of their life in freshwater and then migrate to sea to spawn
What is an example of catadramous?
Freshwater Eel
What does anadramous mean?
Spend majority of life in the ocean, migrate upriver to freshwater to spawn
What is an example of an andramous fish?
salmon
How is age determined in fish?
Growth is measured by otolith body structure in the inner ear.
Layers of calcium carbonate and gelatinous matrix form rings
Are teleosts mono or dioecious?
Mainly dioecious with external development and fertilization
Do fish eggs develop internally or externally?
most develop externally with the exception of few fish that bear live young or incubate their eggs
What does oviviparous?
Bearing live young
