Chapter 14 (forms and function) Flashcards
what are the general ways that fish have evolved?
structural, physiological, behavioural adaptations
what type of fishes do we know the most about, reproductively?
aquarium fishes (primarily Osteriophysi and members of family Cichlidae)
what categories are reproductive guilds separated into?
ecological and ethological
oviparous
lay eggs into their external environment
what are the two general kinds of eggs?
Pelagic (eggs that float)
Demersal (eggs that sink)
what are the three group type of pelagic egg-layers?
1- most all fishes that live over the continental slope
2- nearly all those that range over surface waters of the open ocean
3- all pelagic deep-sea fishes
how do pelagic eggs stay buoyant?
low density fluids or an oil droplet
what happens when a pelagic egg hatches?
releases a colorless larva that, after its yolk sac is used up, survives off of PHYTOPLANKTON AND ZOOPLANKTON
what can be said of the dispersal of pelagic eggs?
survival rate is really low, they have wide geographic distributions
where do most of dermersal egg-layers live?
in near-shore waters, and a lot live between tide marks. tidepool forms
how do demersal egg-layers combat tidepool environments?
sinkable eggs, or anchored eggs to substrate do well here.
geographically, what kind of distribution do demersal eggs have?
restricted geographic distribution
what are some reasons why demersal-egg layers lay fewer eggs?
fishes are smaller, larger eggs, larvae take longer to develop and emerge more advanced in development. also they dont get swept away
what is the danger to demersal,attached eggs? what evolves from this?
predation. they hide their eggs, and develop parental care.
what are five differences between pelagic and demersal eggs?
demersal: large: >1mm gravity: greater egg envelope: thicker Transparancy: opaque amount of yolk: large development: 2 months (a week or less for other)
WHY ARE DEMERSAL EGGS THE RULE FOR FW FISHES?
1: PHYSIOLOGICALLY MORE DIFFICULT to produce an egg w specific gravity less than fw
2: fw DOESNT PROVIDE THE RICH FOOD RESOURCE in its upper layers as does for marine
3: fast rivers/streams REMOVE A LARGE PROPORTION OF EGGS AND LARVAE (limit recruitment)
how many FW species in N. America have pelagic eggs?
ONLY ONE!! (FRESHWATER DRUM (SCIAENIDAE)
what is the correlation between stickiness of eggs and parental care?
nearly all fish deposit eggs that stick or sink. great numbers of non-adhesive eggs get no parental care.
what are some manner of protecting fw eggs?
build NESTS involving COMPLEX BEHAVIORAL DISPLAYS, hide and protect eggs in other organisms (EUROPEAN BITTERLING IN FW MUSSELS)
what is the symbiotic relationship between the bitterling and fw mussels?
mutual exchange of gametes
similarity between ovoviviparous and viviparous
live bearing forms
how do ovoviviparous and viviparous differ?
source of nutrition for developing young.
Ovoviviparous
eggs are retained and fertilized within the body, young get no nutrients from mother. rely on YOLK.
Viviparous
young are nourished by some kind of PLACENTAL CONNECTION with the mother
what do scientists questioning the dichotomy between ovoviviparity and viviparity suggest is a more conservative approach?
call all fish that give birth to live young viviparous (live bearers)
name members who are ovovivi + viviparous
chondrichthyese, live beareres, guppies, fw halfbeak, scorpionfishes (scorpaenidae) surfperches (embiotocidae), brotulas, eelpouts (zoarcidae) clinids, coelacanths
where can you usually find a INTROMITTANT ORGAN used to pass sperm to a female?
usually modified anal or pelvic fins
explain the ovoviviparity in guppies
eggs are fertilized within EGG FOLLICLES or the OVARY. follicles rupture, embryo completes development in the cavity of the ovary. sustained off of yolk nutrients.
Superfetation
maintenance of batches of embryos at various states of development.
explain how developing youngs get nutrition in viviparous forms
placental connection, sometimes walls of ovarian follicle use network of capillaries that extend out as VILLI and make intimate connection with surface of embryos.
some other forms of viviparity
pseudoplacenta, branchial placenta, TROPHONEMA.
trophonema
food absorbing processes that grow out of the hindgut of the embryo
name 4 forms of parental care
1- Male parental care
2- female parental care (ovo w/ post-spwn care), (ovovivi w/o post-spwn care), (vivi w/o post-spwn care)
3-biparental care
4-juvy helpers
describe some forms of male parental care
oral incubators/mouth brooders, bony hook head
where would you generally find the most hermaphroditic species?
in the deep.
what are two types of hermaphroditism, and what defines them?
simultaneous hermaphrodites: produce both egg and sperm.
Sequetial hermaphrotism: can do a sex change, but usually once its done, its done.
WHY SWITCH SEX?
WHICH SEX DO YOU START WITH?
WHEN DO YOU SWITCH?
talk these thru with Jer :)
PROTANDRY. example?
first half of life cycle is spent in the male state. Anenomefishes.
PROTOGYNY
first a female, then a male. (sex switch)
