You are here

mtracy's blog

Gobiifromes - PP

Submitted by mtracy on Sat, 11/17/2018 - 13:58

 

The order of Gobiifromes contains 210 genera and 1,700 species of fish and are some of the smallest known vertebrates. Gobies are primarily marine fish, although they occasionally wander into adjacent freshwater areas. Their pelvic fins are united and form a sucker, which is used to adhere to objects such as plants and rocks. There are some species of sandy substrate dwelling goby which form a symbiotic relationship with shrimp. These shrimp are blind and unable to defend themselves. They will however, dig burrows in the soft sandy substrate in which both organisms may live. In return, the goby alerts the shrimp of incoming danger. There are also species of reef dwelling gobies which exhibit bidirectional sex change. Generally these fishes are protogynus and transition from female to male. Scientist have induced the opposite transition to occur by removing a female in the presence of males. The largest male present will then transition to a female. Likewise when two males were placed in the same area, the largest transitions to female. This is supposedly to have a matching pair of male and female. However it is unlikely this would occur in the wild, as the gobies would be more likely to migrate to a new area as this is more energy efficient.

Percomorpha

Submitted by mtracy on Fri, 11/16/2018 - 11:16

Percomorpha is a vast group of fishes and the groups contained within it are heavily debated and ever changing. Some simply state that it contains "perch like fish." However that is like saying a peperoni pizza looks like a pizza as the perches themselves are a group within the percomorphs. This group contains the families: Batrachoidae, Centraichidae, Percidae, and so forth. The Batrachoidae are the toadfish. These fish have broad eyes which are dorsally oriented so they may peek above the water. This fish also has the ability to make sound using its swimbladder. Centrachidae are the sunfish. These fish are laterally compressed and have a continues dorsal fin with 5-13 spines. These are fish such as the largemouth and smallmouth bass. The perceidae are the Perches. Perches live in temperate freshwater bodies and are a highly diverse group. Examples of perch include the yellow perch, white perch, and walleye.

Gobiifromes

Submitted by mtracy on Thu, 11/15/2018 - 22:21

Gobiiformes is an order of fish containing about 210 genera and 1700 species. Gobies are marine fish which occasionally wander into adjacent freshwater areas. Their pelvic and medial fins unite and form a sucker, which they may use to adhere to objects such as plants and rocks. Some sand dwelling gobies have a symbiotic relationship with shrimp. The shrimp will dig a burrow in the soft sand substrate in which the two organisms live. The goby will then alert the shrimp to danger and they will both burrow deeper. There are also reef dwelling gobies. Some species of reef dwelling gobies exhibit a bidirectional sex change. Generally these go from female to male (protogynus), though under lab conditions the opposite direction has been induced by removing the female. When this occurs the largest male will become a female. If two males are ever placed in the same area, one will change to form a matching pair of male and female. Of course this may only work in lab conditions as in the wild, the gobies will likely simply migrate to a new area.

Hybridogenesis and egg mimicry

Submitted by mtracy on Thu, 11/15/2018 - 19:14

There is another form of parthogenesis used by fish in order to reproduce. This form is called hybridogenesis and is also used by monocha-lucida fish. During this process a diploid ML female will produce a haploid M egg. A haploid L sperm will join with the egg, though a female is always produced by this process. However once fully maturing as an adult, the paternal portion of the genes is discarded and the female will once again only produce haploid M eggs, and the cycle repeats.

Other fish use a variety of methods to attract their mates. For instance, some will have physical traits which monopolize on certain behaviors of the other sex. For example, many female fish carry their eggs in their mouths for safety, even before fertilization. Males of this species may produce structures on the ends of their fins which mimic the appearence of eggs. The female will therefore attempt to carry the mimic eggs in its mouth, at which time the male will fertilize the eggs already in the females mouth.

Fish reproductive strategies

Submitted by mtracy on Tue, 11/13/2018 - 09:56

There are many reproductive strategies that fish use. For instance, many fish species reproduce through polygyny, where 1 male will have multiple partners. With this method, the female partners usually choose the territory, not the male. A male will determine and defend its territory and build nests which the females will visit or say in. This of course depends on how sutible the nest or territory is. Fish which are polyandrous have 1 female which reproduces with multiple males. An example of this is the anglerfish. The female in this species is very large. Males are tiny tadpole looking fish, which latch onto the female. Eventually these males become parasitic and literally fuse with the female, becoming a sort of male gonad on the female. This even goes so far as to share the same ciruclatory system. Whenever th female wants to reproduce, the male is signaled and sperm is released into the eggs, fertilizing them.

MLL Gynogenesis - PP

Submitted by mtracy on Sat, 11/10/2018 - 12:35

 

Some fish species reproduce through a method of parthenogenesis called gynogenesis, in which a female will produce an already fertilized and viable egg. This method may be observed in Poeciliopsis monocha and Poeciliopsis lucida. Normally there is a breeding population of diploid fish of each of these species. However, there is also a triploid population of female only monocha-lucida-lucida fish (MLL). These fish produce triploid MLL eggs. Oddly enough, even though there is no genetic transfer between egg and sperm, a diploid lucida sperm is still required in order to activate the MLL egg. Once activated, this egg will develop into a female MLL adult. The fish that comes from this egg is always a triploid female, a genetic clone of its mother and all the fish in its lineage before it.

Gynagenesis in monocha lucida

Submitted by mtracy on Thu, 11/08/2018 - 22:50

There are some fish species which reproduce through parthenogensis. This may come in at least two froms, gynagenesis and hybridogenesis. One example of gynagenesis is with fish carrying monocha (M) and lucida (L) genes. Some females are triploid and carry MLL. These females will produce a triploid egg, also MLL. A diploid LL fish will release its L sperm in order to "fertilize" the MLL egg. There is actually no genetic transfer in this process, the sperm only stimulates the MLL egg. Once successfully stimulate, the egg activates and a new triploid MLL female (yes always female) fish is born. So where do males come from if all that is produced from this process is females? The normal diploid population, which is favored by diploid males. Therefore, there are two seperate populations. A diploid population of both males and females and a triploid population of all MLL female clones.

Rivulus Reproductive Strategy

Submitted by mtracy on Wed, 11/07/2018 - 16:17

Rivulus, a genus of freshwater fish, has a very odd reproductive strategy. This fish is hermaphroditic, which in itself it not too uncommon among fishes. Rivulus is able to self fertilize, though not in the way that a majority of self fertilizing fish do. Most fish which reproduce by this method are females which produce fertilized eggs, more or less producing clones of itself. The drawback to the strategy is it limits genetic diversity. The rivulus however, will produce both sperm and eggs. When gametes are formed during meisos, Rivulus will therefore maintain the "crossing-over" phase which most other hermaphorditic fish lack. This gives the fish the ability to maintain some level of genetic diversity among its populations. Of course this diversity is still limited by the fact that there isn't multiple populations mixing.

Lampriformes and the Giant Oarfish

Submitted by mtracy on Tue, 11/06/2018 - 14:43

The order Lampriformes is largely catagorized by morphological features. Fishes in this order have a Mesethmoid bone posterior to their lateral ethmoids, an elongated premaxilla, their first dorsal pterygiphore insterts anterior to their first neural spine and have the absence of a platine prong. Oarfish, Lampris and apahs are all examples of Lampriformes. The giant orfish, of the family Regalecidae is known as the king of the herrings. This fish is a very elongate and slab sided. The giant oarfish has a tube shaped mouth, which it uses to suck in its prey. Furthermore it has a very large eye and red fins. The most notable feature of the Giant Oarfish is its crownlike spines on the top of its head, which are fused with its dorsal fin and follows the entire length of its body. The Giant Oarfish is a very large fish and can reach up to 11 meters in length. Its body stays ridgid as it swims, but sends sin waves down its long dorsal fin to propell itself. There is a notable absence of scales on the oarfish as well.

Georges Banks

Submitted by mtracy on Sat, 11/03/2018 - 22:22

 

Georges bank is a region of ocean just south of the Gulf of Maine and East of cape cod Massachusetts. This region is only 45 meters deep, allowing sunlight to reach the bottom making it very nutrient reach. Furthermore, the gulf stream and Labrador current intersect here, bringing their own nutrients and “mixing it up.” The cold water makes it perfect for the Atlantic cod and a variety of other fish species. Due to this large productivity, Georges Banks has been an important economic fishing zone. Unfortunately overfishing over the last hundreds of years has decreased the biomass of this area by nearly 90%. 66% of this decline has occurred in the last 50 years alone. Unfortunately this does not seem to be changing, despite attempts of (admittedly insufficient) regulation. Recent fears of global warming seem to be effecting the gulf of Maine significantly. Unfortunately the fish here are adjusted to live in the cold waters, and as water temperature rises it will only get harder for them to survive here. Not only is the loss of fish species tragic on its own, but we as humans rely on this area for food and money.

Pages

Subscribe to RSS - mtracy's blog