Week 14 Flashcards
Why are measurements of the fish important?
These measurements can then be used to quantify and standardise certain aspects of the morphology of the organism. Through this we can make accurate comparisons between different species, and hypothesise on the reasons behind these differences.
What is the standard length of a fish?
The standard length of a fish is the distance from tip of the snout to the start of the tail fin (caudal fin). Alternative measurements include, fork length and total length which you will learn about during the practical.
What is the aspect ratio of a fish?
The aspect ratio of the caudal fin is used to indicate the type of lifestyle or propulsive ability of a fish. It can be used to compare and differentiate different species, such as, fast swimming, pelagic species and slower, bottom dwelling species.
What is the equation for calculating aspect ratio?
The equation for calculating the aspect ratio of the caudal fin is A = h2 / s where h is the height, and s is the surface area.
Aspect ratio= height2/surface area
Why is the gill arch important in this experiment?
the gill arch found in teleost fish.
The morphology of the gill arch can vary across species, and can be highly informative as to the ecology of the fish.
What are the two teleost fish used in this experiment?
Each group has specific features, both ecological and morphological, which you will need to identify in other species.
Pelagic species
Demersal species
What are the pelagic species?
These species inhabit open waters, and have various adaptations for this habitat
What are the Dermersal species?
Demersal species are bottom dwelling, benthic organisms. The evolutionary pressures of these species are markedly different from the pelagic teleosts, and their morphology, ecology and behaviour reflect this.
Note that some demersal species can have features similar to pelagic species, but they do not have all the features that pelagic species have.
Which of the following are characteristic of pelagic fish species?
Forked caudal fin
Streamlined shape
Counter shaded body (dark on top, light underneath)
Found in open water column
Which of the following should be included when producing good biological drawings?
Good biological drawings should be made up of single pencil lines using a sharp pencil.
Drawings should include a scale bar so the original specimen size can be estimated.
Colours and shading should be described in labels and annotations.
_____ fishes evolved at the same time as sharks, some 400 million years ago.
Blank 1: Bony
Select all that apply
Choose all features typical of most bony fishes.
Lack of swim bladder
Completely symmetrical tails
Internal skeleton made of bone
Thick, protective scales
Highly mobile fins
Completely symmetrical tails
Internal skeleton made of bone
Highly mobile fins
Two important adaptations that enabled the remarkable success of the bony fishes are the swim ______
and the _____ cover.
bladder
gill
The oval body releases gas from the _____ bladder of fish, thereby playing a role in their buoyancy.
swim
Most bony fishes possess a _____ ______ ,a gas-filled sac used to maintain and control buoyancy.
swim bladder
When did bony fishes evolve?
At the same time as sharks
Bony fish have a bony ____ and a skin covered in plates or _____.
skeleton
scales
Select all that apply
Which of the following adaptations were particularly important in the success of the bony fishes?
The lateral line system
The swim bladder
The gill cover
Gill arches
The swim bladder
The gill cover
The swim bladder of bony fish evolved as a dorsal outpocketing of which of the following structures?
Pharynx
Select all that apply
Which of the following do not possess a swim bladder?
Tuna Flounder Rays Sharks Skates
Rays
Sharks
Skates
The ______ is the hard plate that covers the gills in bony fish.
operculum
Which of the following are features of bony fishes?
All have a bony skeleton
Most have a scale-covered skin
All bony fishes have lungs
Most bony fishes exhibit internal fertilization
All have a bony skeleton
Most have a scale-covered skin
Which of the following are major groups of bony fish?
Myxini Sarcopterygii Chondrichthyes Actinopterygii Cephalaspidomorphi
Sarcopterygii
Actinopterygii
In ______-finned fishes, each fin consists entirely of parallel bones and is moved by muscles inside the body, whereas in ______-finned fishes, the fins have muscles and a central core of bones that form an articular joint.
ray
lobe
The oval body releases gas from the ____ bladder of fish, thereby playing a role in their buoyancy.
swim
The ____-finned fishes evolved 390 mya, shortly after the first bony fishes appeared in the fossil record.
lobe
When bony fish flex the operculum ____
is pumped over their gills.
water
Which of the following accurately describes the fins of ray-finned fishes and lobe-finned fishes?
In ray-finned fishes, muscles within the fins cause the fins to move
In lobe-finned fishes, each fin is made of a long fleshy muscular lobe
In ray-finned fishes, each fin consists of parallel bony rays
In lobe-finned fishes, there are bony rays at the tips of each fin
In ray-finned fishes, each fin consists of parallel bony rays
In lobe-finned fishes, each fin is made of a long fleshy muscular lobe
In lobe-finned fishes, there are bony rays at the tips of each fin
Which of the following classes appeared in the fossil record shortly after the appearance of the first bony fish, around 390 million years ago, and eventually contained members that colonized the land?
Sarcopterygii
What are the only living relatives of the jawless vertebrates?
If we look at the jawless vertebrates- you will see that the lampreys and the hagfish, which are the only living representatives of the jawless vertebrates
What gave rise to the jawed vertebrates?
You can see that the jawless vertebrates gave rise to the jawed vertebrates. We have a distinct lineage called the placoderms, that is sister to the extent lineages, of the Chondrichthyes and also the bony fish.
What does the most recent paleontological evidence indicate?
that there were many lineages of jawless vertebrates, some living (lampreys, hagfish), many extinct (e.g. conodonts).
What shares a common ancestry with the living jawed vertebrates?
The placoderms share common ancestry with the living jawed vertebrates, and this combined monophyletic group is the Gnathostomata (Gnathostomes)
What does the Gnathostomes contain?
The Gnathostomes contains extant Chondrichthyes (sharks, skates and rays) and Osteichthyes (bony fishes).
The Osteichthyes (Osteichthyans) contains the
the ray-finned fishes (Actinopterygii) and the lobe-finned fishes (Sarcopterygii).
The lobefins include the
the coelacanths, lungfishes and the tetrapods (amphibians, reptiles and mammals).
What can the Osteichthyes be separated in to?
can be separated into two major groups. One of those is the Actinopterygii which are the ray finned fishes. The second is the Sarcopterygii which are the low fins. The low fins include the Coelacanths, lungfish, and all the tetrapods.
How are the ray finned fish divided?
The ray finned fishes are divided into three main groups. I) The Chondrostei which comprises the bichirs, sturgeons and paddlefishes. II) The Holostei which comprises the bowfins and the gars. III) The Teleostei, which comprises all other ray finned fishes.
How many teleost fishes are there?
There are estimated to be around 30,000 teleost fishes, and they started to diversify around 300 million years ago.
What are the Chondrostei Characteristics?
First, focus on the Chondrosteans (Chondrostei). These are a group of bony fishes, that actually have cartilaginous skeletons. However, it is clear from the fossil record that their ancestors had bony skeletons and these have been “secondarily lost”.
1.Secondary loss of bone
Skeleton mainly cartilage
No vertebrae
What do the Chondrosteans have the remains of?
also have the remains of a spiracle (which has homology with the first gill slit of the agnathans – the lampreys and hagfishes).
2.Presence of spiracle
Remnant of 1st gill slit of agnathans
chondrosteans have
“ganoid” scales, which are characterised by three layers (enamel, vascular bone, lamella bone).
- Ganoid Scales
- –3 layers- Enamel, Vascular bone and Lamella bone.
What are the characteristics of the ganoid scales?
This ganoid scales which are found in the Chondrosteans are also found in the Holostei. They’re quite different from the scales that we see in the Teleosts.
How are the Teleosts characterised?
Teleosts are either characterised by their cycloid scales or ctenoid scales, these have only a lamella bone layer with very little mineralisation.
–By contrast the teleosts have cycloid and/or ctenoid scales, and these are much lighter, with only lamella bone without much mineralisation
What are the Chondrostei: (Polypteriformes)?
Modern chondrosteans are species poor. There are only two living Orders.
The first Order is the Polypteriformes, otherwise known as bichirs, and there are 12 living species. These are typically found in shallow swampy African freshwaters, and they have paired lungs that can help to breathe in poorly oxygenated waters.
What is the second order of the Chondrostei?
The second Order is the Acipensiformes, a group that contains the paddlefishes (1 living species) and the sturgeons (27 living species).
Outline the features fof teh American Paddlefish?
Here is the American paddlefish, which live in rivers of North America. They are notably for the extremely long paddle-like rostrum that contains electroreceptors capable of detecting the presence of their favoured prey in the water column. These are essentially filter feeders, they open their mouths up really wide and filter the zoo plankton from the water using their Gill rakers.
A second paddlefish species, the Chinese paddlefish, was native to the Yangtze and Yellow River basins in China. The last sighting was 2003, and it was declared extinct by the IUCN in 2020, as a consequence of overfishing and habitat destruction/fragmentation.
What are the sturgeons?
The sturgeons are a group of large migratory species broadly distributed across the northern hemisphere. They are threatened by overharvesting and blocking of migration routes. Caviar (eggs, roe) is harvested from several large species, meaning that they can be valuable for illegal fishers. Anadromous, long lived and 8m long 1.4 tonnes.
What are the Holosteans (Holostei)?
Like chondrosteans, these species also have spiracles, but these are non-functioning in gars. They have ossified (bony) skeletons, but this is still partially cartilaginous in bowfins. They have the ganoid scales, also like chondrosteans.
What are the three features of Holosteans?
Spiracles present (but not linked to outside in gars)
Ossified (remains of cartilaginous skeleton in bowfins).
Ganoid scales, 3 layers: Enamel, Vascular bone and Lamella bone.
What are the two lineages of Holosteans?
There are two main lineages, but these are actually quite distantly related.
The first is the Amiiformes, which only has one living species, the bowfin (Amia calva) that lives in North American freshwaters.
The second is the Lepisosteiformes (Lepisosteidae), or the freshwater gars, which has 7 living species, again mostly in North American freshwaters.
What does a phylogenetic tree tell us about the diversity of Teleosts?
Now let’s look at the diversity of teleosts. Here is a phylogenetic tree based on using nuclear DNA sequences, and fossil calibrations.
This tree has confirmed origins of the teleosts date to 300Ma, and have resolved the complex relationships within the group.
Specifically, this tree has identified five major lineages within the teleosts, the Eopomorpha, Osteoglossiformes, Otocephala, Protacanthopterygii and the Neoteleostei. And next we will look briefly at those five major groups.
What are the Elopomorpha?
they have two morphologically divergent groups of species, which contains the tarpons and eels, note the shared leptocephali larvae. Laterally compressed almost see through lava, which is unique to this group.
What are the Osteoglossoformes?
(bony tongues), which contains the mormyrids, arowana, featherfin knifefishes. Morphologically diverse.
What are Otocephala?
which is a very morphologically diverse group of herrings, catfishes, knifefishes, cyprinids. This is a newly defined group based on molecular evidence. Most of these taxa (except the herrings) possess a Weberian apparatus (an anatomical structure connecting the swimbladder to the auditory system),
What are Protacanthopterygii?
also a diverse group, but share many characters, including an adipose fin, and they lack a protractible upper jaw. Includes the barreleyes, such as Macropinna.
What are the Neoteleostei?
A remarkably diverse group, sharing traits such as the pharyngeal retractor muscle. Includes seahorses etc. range of different habitats.
What does evidence suggest about marine and freshwater environments?
Evidence suggests that there have been many evolutionary transitions between marine and freshwater environments (Betancur-R et al. 2015, Ecology Letters). There are also many true euryhaline species (i.e. can live within a wide range of salinities). Maps on the transition between marine and freshwater environments during the evolutionary history of the group. Most likely that the ancestry hosts were marine, but they have repeatedly colonised freshwater environments during their evolutionary history.
The teleosts are characterised by the following traits:
High species richness in many teleost lineages, coupled with morphological, ecological and behavioural diversity. Depth, habitat and colour differences among sister species are commonplace.
High species richness in many teleost lineages, with some families within the group possessing 200+ species. Examples of families with high species richness include the freshwater cichlid fishes (=Cichlidae; 1800+ species) and the marine lanternfishes (=Myctophidae; 300+ species).
Sister species commonly differ in depth, substrate, diet and body colouration. Together these patterns suggest that the rapid speciation observed in many teleost lineages has been promoted by both divergent natural (=ecological) selection, and sexual selection.
Here is an example of two pupfishes from a lake in the Bahamas. These are sister species, but one feeds in scale, while the other feeds of molluscs. To study how new species evolve, we often study teleost species pairs like this.
Teleosts have commercial and societal importance. They are extensively used in scientific research, particularly medical research. To understand the function of a vertebrate gene, it is commonly manipulated in zebrafish to determine the outcome. It has been chosen because it has a very fast lifecycle (3 months) and large eggs that are easily harvested.
Finally, teleosts are of considerable commercial importance as a food, both directly for humans, but also indirectly for livestock. Wild (capture) fisheries are now maximally exploited globally, so there is considerable investment in aquaculture, in cages in the sea, cages in lakes, and in ponds.
What are the major marine species?
Major marine species: Peruvian anchovy, Alaska pollock, Skipjack tuna etc.
What is the swim bladder?
An important feature that sets teleosts apart from other fishes
Can adjust the relative density of the teleost, determining buoyancy.
What do Teleost skeletons have?
Teleost skeletons can have a lot of heavily calcified bone - in other words, in addition to cartilage their skeleton contains a lot of calcium phosphate. This makes teleosts relatively heavy in comparison to species with cartilaginous skeletons. Swim Bladders help fish to achieve neutral buoyancy, they have evolved.
What essentially are swim bladders?
Swim Bladders are essentially gas bladders, that are situated towards the dorsal surface of the abdominal cavity, and the gas within them can be adjusted, gas can be pumped into the bladder and that will provide more buoyancy but it is also possible for gas to be removed from the bladder, providing less buoyancy. The fish will adjust the content of their swim bladder depending on what the need is of that particular point in time.
How does the swimbladder function?
Oxygen-rich blood flows from the aorta (red) through the swimbladder organ capillaries, into the veins (blue).
To pump gas into the bladder, blood flows through the vessels of rete mirabile (a network of capillaries), and into the gas gland, where gas to enters the bladder. The gas gland excretes lactic acid, makes carbon dioxide, causing haemoglobin to lose oxygen (the so-called root effect), which diffuses into the bladder.
What does the rete mirabile also do?
However, the rete mirabile also acts like a pump. As it flows back through the rete mirabile from gas gland, excess oxygen and carbon dioxide are absorbed into the neighbouring vessels going into the gas gland, generating pressure, allowing high pressures to develop in the gas bladder. This is how high pressure develops in the gas bladder.
How is gas removed from the bladder?
To remove gas from the bladder, blood flows through the ovale (oval window) and the rate of oxygen removal is related to the flow of blood controlled by sphincter muscles.
Why does the swim bladder need layers?
To hold gas a high pressure, the swim bladder needs to be both strong and elastic. The outer layer is made of guanine crystals and elastic fibres, while the inner layer is collagen, but also smooth muscle and nerves are present.
What is in the outer later of the swim bladder?
guanine crystals and elastic fibres
What is in the inner layer of the swim bladder?
Collagen and smooth muscle and nerves.
The ability of a swim bladder to function is governed by
the density of the surrounding water.
Here a 1kg teleost fish, without a swimbladder, will sink in freshwater, as it has a higher density (~1.08) than freshwater (~1), and therefore a volume of 1/1.08 = 0.926 litres.
Since that fish would has a volume of 0.926l (=926ml) it would need 74ml of gas to be buoyant.
The same 1kg teleost fish, without a swimbladder, will also sink in seawater, as it has a density (~1.08) than seawater (~1.026), and therefore a volume of 1.026/1.08 = 0.950 litres.
Since that fish would has a volume of 0.950l (=950ml) it would need 50ml of gas to be buoyant.
It is possible to work out how much gas is needed for buoyancy in any particular aquatic environment and second because seawater is denser it requires less gas than freshwater to make a fish achieve neutral buoyancy.
