Exam 2 Flashcards
What is the most primitive living vertebrate?
hagfish
What do marine organisms get more of in comparison to freshwater organisms?
electrolytes
Do hagfish have jaws?
no, they are jawless
Since hagfish have no jaws how do they go about feeding?
they have keratinized teeth that rasps tissues and a muscular tongue
What does a hagfish primarily eat?
dead or dying fish
What is a hagfish also known to eat besides dead or dying fish?
marine worms and crustaceans on the ocean floor
What is a hagfish’s mouth surrounded by and what are they used for?
tentacles, they are used for touch
Why do hagfish have tentacles for touch instead of relying on their eyesight?
they have degenerate eyes that are covered by thick skin, this makes them have a keen sense of smell and touch
How many gill slits do hagfish typically have?
multiple, however other species can have over 10 pairs on each side
Do hagfish have a primitive lateral line system?
yes
What kind of kidneys do hagfish retain into adulthood?
primitive kidneys “pronephros”
What are primitive kidneys?
they are kidneys normally only seen in embryonic development
Hagfish are isosmotic, what does this mean?
its osmolarity is the same as its environment
What environment does a hagfish live in?
marine environments (saltwater)
What is osmosis?
diffusion of water though a semipermeable membrane
What does the word “osmolarity” refer to?
the number of solute particles in a fluid
What is osmotic pressure?
the pressure that is required to stop osmosis
What is the osmolarity of sea water?
1000 mOsm
What is the osmolarity of freshwater?
20 mOsm
What is the osmolarity of mammals body fluids?
300 mOsm
What other organisms are also isosmotic?
the protochordates (tunicates and amphioxus)
Are invertebrates isosmotic?
yes
What is the purpose of the hagfish’s accessory hearts?
They are in the venous system and help pump blood back to the main heart
What does the body of a hagfish have and produce?
their bodies have slime glands that open to the outside of the body through many pores
What is the purpose of the large amounts of slime produced by hagfish?
it is a defense mechanism
What are hagfish known as to fisherman?
slime eels
What is the hagfish’s knotting behavior used for?
rid themselves of slime, also to gain traction while eating or trying to flee predators
Where do all hagfish dwell in the ocean?
they are bottom dwellers in relatively deep waters (300 ft or more)
What is the sexual reproductive system of a hagfish?
they have a single long gonad and non reproductive ducts
What kind of fertilization is present in hagfish and how does it work?
external fertilization: gametes are given off into body cavity and then exit through a pair of genital pores into the cloaca
Is there a larval stage in the hagfish?
no
Is there an economic significance to hagfish?
yes, their meat is eaten in some parts of the world and their skin is used to produce “eel skin” for leather goods
How many pair of gills and gill opening do lampreys have?
7 pairs
What is the lampreys one nostril used for?
olfaction
What is well developed in a lamprey?
their eyes and their lateral line system
Do lampreys have accessory hearts?
no
What is the osmolarity of a lampreys body?
approx. 300 mOsm
Do lampreys have well developed kidneys and ion pumps on gills?
yes
Lampreys are _______ to seawater and ________ to freshwater.
hypo-osmotic; hyper-osmotic
Do lampreys live in marine water or freshwater?
they’re anadromous, they live in marine water and travel to freshwater to reproduce
How many species of the lamprey are parasitic?
18 species
How do lampreys feed?
sucker life mouth with keratinized teeth and tongue with teeth, they attach by suction and use teeth to rasp skin away
What do parasitic lampreys secrete”
anticoagulant
Non parasitic lampreys have what kind of digestive tract?
degenerate; so as adults they don’t feed
How long do non parasitic lampreys live?
only a few months
What do lamprey eggs develop into?
ammocoete larva, meaning it is distinctly different from the adult body form
What do ammocoetes do through their long larval stage?
dig into the bottom of streams and filter feed
How long may ammocoete larva feed before they undergo metamorphosis into an adult lamprey?
3 to over 8 years
How long do parasitic lampreys feed before reproducing?
1-3 years
What happens to anadromous forms of the lamprey?
adults migrate to freshwater to spawning and die soon after spawning
When do non parasitic lampreys breed?
soon after metamorphosis and then die
Can some species of lamprey live entire life in freshwater? what is an example?
yes; lamprey in the great lakes
How are lampreys of economic importance?
they negatively impact, they get rid of and eat other important fish
When do the first jawed fish appear in the fossil record?
silurian period
What did the development of jaws to for feeding capabilities?
increased them and allowed for new food sources
What else did jaws allow for?
new behaviors such as digging of nests
How do embryological and anatomical studies suggest that jaws may have developed?
through modification of several sets of anterior gill arches
What did early jaws fish also have and what was its function?
paired fins which enhanced their ability to control their movements and allows them to better use their jaws
What are the two earliest groups of jawed fishes?
acanthodians and placorderms
Describe Acanthodians.
appear to be first jawed fish in fossil record
name refers to their stout spine
structurally appear to be related to modern fish
Describe Placoderms.
appear slightly later than acanthodians
body covered with thick bony shields
When were both Acanthodians and Placoderms flourishing and when did they decline and become extinct?
Devonian; Carboniferous and Permian
What animals are in the class Chondrichthyes?
sharks, skates, rays, chimeras
What animals are in the class Elasmobranchs?
sharks, skates, and rays
When do the fossils of early shark like Chondrichthyes date back to?
late silurian and the Devonian period
What is an example of the early shark like Condrichthyes?
Cladoselache
When did Cladoselache become extinct?
during the carboniferous
Chondrichthyes was the first jawed fishes with what kind of skeleton?
cartilaginous
What kind of tail do sharks have?
heterocercal
What kind of scales does the class Chondrichthyes have?
placoid, however chimeras have no scales
What do placoid scales help with?
reduce turbulence when swimming
What do the mucous glands in class Chondrichthyes help with?
prevent abrasions, infections, decrease predation, and decrease drag while swimming
How are sharks usually identified?
by their tooth structure, because teeth are species and genus specific
Are jaws firmly attached to the cranium in Chondrichthyes?
no, except in the chimera
Why are the jaws not attached to the cranium in class Chondrichtyes?
so they can be extended when feeding
Can sharks swallow prey whole?
yes, they can even be known to attack whales
Does class Chondrichthyes have a gas bladder?
no
How can the gas Chondrichthyes have buoyancy with no gas bladder?
their buoyancy is aided by large amounts of oil in the liver (squalene oil)
What percent of Chondrichthyes body weight is the liver? What percent of the weight of the liver is attributed to oil?
25%; 80%
What are the differentiated lobes in the brains of Chondrichthyes?
olfactory, optic, cerebrum, and cerebellum
How many cranial nerves do Chondrichthyes have?
10 pairs
How many loops does condrichthyes semicircular canals have?
3
Chondrichthyes has well developed what?
olfaction and lateral line system
What is the Ampullae of Lorenzini?
electroreceptors on the nose of Chondrichthyes
What kind of changes do the Ampullae of Lorenzini detect?
temperature changes
What kind of feeders are sharks?
nocturnal feeders
How do shark eyes work in low light?
mirror like layer behind the retina to reflect light and enhance vision; their lens also moves back and forth to focus on objects at different distances
What is the sharks additional eyelid called?
nictitating membrane
What does Chrondichthyes digestive system have?
stomach, liver, gall bladder, pancreas, and large spiral valve in intestines
What is the function of the spiral valve?
slows the passage of food and increases surface area available for digestion
What kind of heart does Chondrichthyes have?
2 chambered heart
How is blood pumped through the body of Chondrichthyes?
from heart to gills then to the body; its a low pressure system
What is the function of the rectal gland?
secretes concentrated salt solution into cloaca, helps regulate proper salt concentration in blood and body fluids
Are sharks isosmotic to sea water? if so what is their osmolarity?
yes, 1000 mOsm
Describe the reproductive system of Chrondrichthyes.
gonochoristic
have paired gonads and reproductive ducts
ducts connect to cloaca (except in holocephali)
What is the function of the cloaca in Chondrichthyes?
chamber that receives material from the urinary , digestive, and reproductive system
What allows for internal fertilization on sharks?
claspers
What is oviparous?
embryo & nutrients are sealed in an egg case and released into the water
What is an egg case made out of?
keratin
How long does it take for an egg to hatch?
6 months to over a year
What is ovoviviparous?
embryo & nutrients are deposited in the oviducts and can be surrounded by a thin egg case; develops within mother and is “born”
How long does it take an egg to hatch in the mother?
9 months to well over a year
What is viviparous?
direct connection between mother and embryo; embryo and yolk are deposited in oviducts, embryo also receives nutrients via blood vessel in yolk sac (primitive placenta)
How long does a placenta attached embryo take to be born in a mother?
8 months to well over a year
Is shark meat a popular good in some areas of the world and even in the U.S.?
yes
What is skate and stingray meat sold as?
“scallop” meat because it has a similar taste and texture
What is shark finning?
catching sharks for fins while throwing away the rest of the body
Is shark skin used for leather?
yes
Shark liver oil has be sold as a health supplement, why?
rich in vitamin A and has a variety of “unsubstantiated” health benefits
What are shark populations susceptible to and why?
excess commercial fishing because they are slow growing and slow to mature
What is an example of shark that has been overfished?
the porbeagle shark in western North Atlantic
Why are there laws that regulate the number of shark species that can be captured each year?
in order to maintain “maximum sustainable yields” of each catch
What animals are in Holocephali?
chimeras (ratfish or rabbitfish)
What are the physical characteristics of chimeras?
fish like body with long flexible tail
large venomous spine of the first dorsal fin
large eyes
What are the function of chimeras large eyes?
help vision in dim light, possible seeing bioluminescent organisms
What are chimeras considered to be condrichthyes?
they have a cartilaginous skeleton, spiral valve, oil filled liver, and claspers in males
What are the differences between chimeras and sharks, skates, and rays?
upper jaw is firmly attached to the skull
single gill flap, no spiracle
no scales
no cloaca (they have separate openings for reproductive, urinary, and digestive systems)
Where to chimeras inhabit?
marine waters and typically deep and offshore
What do chimeras feed on?
mainly shellfish and other invertebrates
What do chimeras have that help them crush shellfish?
plate like teeth
How do chimeras reproduce?
they are oviparous, their young develop in egg cases that are deposited on the bottom
What is the class of Elasmobranchs divided into?
Batoids (55% of species)
sharks (45% of species)
How are batons thought to be derived?
from shark like ancestors
When are the earliest fossils of batoid found?
the jurassic period; relatively recent in comparison to shark like condrichthians
What is the general morphology of Batoids?
body flattened dorsoventrally
enlarged pectoral fins (used for swimming)
spiracle on dorsal surface & gill slits on ventral surface
reduced tails or tail spines with venom
plate like teeth for crushing prey
Where do Batoids look for prey?
on the bottom of the ocean floor
How does the spiracle work in species which lay on the bottom of the ocean floor?
water is taken through the spiracle and pushed out of the ventral gill slits
In what kind of water do Batoids inhabit?
most are marine, but some ‘euryhaline’ can travel into freshwater
Since most Batoids are bottom dwellers what behavior do they exhibit?
often bury themselves in the bottom sand
What do most Batoids feed on?
crustaceans, mollusks, and other invertebrates found on the bottom
What are examples of the diversity in batons?
guitar fish
saw fish
skates
rays
Describe the guitar fish.
intermediate between skates and rays
propels itself with tail
spiracle on dorsal surface, gill slits on ventral
uses snout to burrow while looking for food
contains electroreceptors
What do guitar fish feed on?
mollusks, crustaceans, worms, and fish
How do guitar fish reproduce?
ovoviviparous (produce live young)
In what habitat are guitar fish found in?
shallow coastal waters and up into estuaries; and possibly rivers
Describe sawfish.
spiracle dorsally, gill slits ventrally
similar shape to guitar fish
teeth are modified placoid scales
contains electroreceptors
How can a sawfish use its “saw”?
slash through schools of small fish to stun prey and break up the schools
stir up bottom to uncover prey
defend itself against predators
Where do sawfish primarily inhabit?
marine environments but some are found in freshwater (euryhaline)
How do sawfish reproduce and what’s a detail about the babies?
they’re ovoviviparous; teeth on saw of baby is covered with skin to prevent damage to the mother
Are all species of saw fish endangered?
yes
What was the first marine fish to be put on the endangered species list in the U.S.?
saw fish
Describe skates.
ventral gill slits
dorsal fins near tip of tail & thorn like spines along back and tail (no long sharp spine)
What do skates feed on?
feed on invertebrates on the bottom
How do skates reproduce?
oviparous and produce eggs (mermaids purse eggs)
What is the most abundant skate in Alabama?
clearnose skate
Where are sawfish reported to live?
Gulf of Mexico & Atlantic waters of U.S.
freshwater lake Nicaragua
rivers in Australia
Describe rays.
whip like tail
dorsoventrally flattened
How do rays reproduce?
ovoviviparous