Plankton

Plankton is any drifting organisms that are found in aquatic environments, which includes marine and fresh water. They are the base of the food chain for aquatic organisms such as fish and cetacean. Plankton food chain is responsible for the survival of many of the sea creatures. A fictional character of American cartoon series is named on this species and that is “SpongeBob SquarePants”.

Plankton can be divided into broad functional (or tropical level) groups:

• Phytoplankton: These are tiny algae that live near the water surface as there is sufficient light to support photosynthesis. They are usually unicellular. The more important groups among them are the diatoms, coccolithophores, cyanobacteria and dinoflagellates.

• Zooplankton: These are the small protists or metazoans (i.e., crustaceans and other animals). Small fishes consume the zooplanktons. 

• Bacterioplankton: These include bacteria and archaea, which play an important role in nutrient cycles in the water column.

The plankton is divided into the broad categories such as producer, consumer and recycler groups. Though most dinoflagellates are either photosynthetic producers or heterotrophic consumers, some can do both depending upon the circumstances. 

Among the plankton, holoplankton are those that spend their entire life cycle in the plankton, whereas meroplankton are those organisms that are planktonic for only part of their lives (generally the larval stage), and then move into the nekton or a benthic habitat. Some of the examples of meroplankton consist of larvae of sea urchins, starfish, clams, crustaceans, worms and most fish.

Planktons have a demerit that they are unable to swim against ocean currents like the fish and squid. They have a characteristic that they live in deeper water during the daylight, which provides protection from predators. This behavior is common in different phyla that are in the plankton. 

The abundance and distribution of plankton are strongly dependent on factors such as nutrient concentrations, the state of the water, and the abundance of other plankton. The primary sources, which are responsible for this variability, are the availability of light and nutrients. As springtime brings increased light and higher temperatures, this result in a spring bloom of phytoplankton, followed by zooplankton. During the summers, dead organisms sink to the bottom and then the bacteria and fungi both break down the tissues in the process of decay. The nutrients get restored, which concentrate on the bottom. Thus, the rate of photosynthesis declines. The warmer water stay on top and cooler water stays on the bottom. And if the water movements bring the regenerated nutrients up closer to the surface, then the phytoplankton bloom again. In the winter, temperatures fall and now the cooler surface water sinks down, and bottom water comes up. It causes the stratification to break down and another small bloom to occur.

Importance to Fish

Zoo plankton behaves as the initial prey for almost all the fish larvae. The density and distribution of these zoo plankton supports the life of the fish larvae, otherwise they will starve. If the zoo planktons get affected by the natural factors or man-made factors, then the result will be directly seen on larva’s life.

Types of Seal

The fin-footed mammal belongs to the Pinnipedia family. There are about 33 known different types of seals. The family of Pinnipedia is divided into 3 different sub-families know as the Odobenidae, Otariidae and Phocidae. The types of the seals are as following:

Leopard Seal (Hydrurga leptonyx) : It is the second largest and most aggressive seal of all the species. They live in Antarctic Ocean. They feed on krill, fish and small marine creatures, and like fresh caught penguins. Their life span is of 26 years.

Harp Seal (Pagophilus groenlandica): It has brown or black furs and look like a polar bear when they are young. They are found on the coast of Atlantic and Arctic Ocean. They grow up to 5.6 feet in length. Their average life span is of 30 years.

Harbor seal (Phoca vitulina): It grows up to an average height of 6 feet. They are found in Pacific Ocean, Atlantic Ocean, Arctic coastline and Baltic Sea. Their life span is 20 to 35 years for males and female respectively. When compared with other seals they are normally smaller.

Gray seal (Halichoerus grypus): They are of brown and dark gray color and grow up to the length of 10 feet. Their life span is about 30 to 40 years.

Northern Elephant seal ( Mirounga angustirostris): These seals are large and grow up to a size of 14 feet in length. They are of light gray and dark black color. They feed on marine animals and most probably hunt at night.

Southern Elephant seal (Mirounga leonine): These are the largest seal in the world. The males of these species make a roaring sound during the breeding season. They feed mainly on fish, squid and penguins.

Weddell Seal (Leptonychotes weddellii): These seals grow up to a size of 10 feet. They are found mainly in McMurdo. In addition, they are very calm in their nature. They look very funny when they lie on their backs and hold their stomach with their flippers and mouth open. It seems that they are laughing holding their stomach.

Hawaiian seal (Monachus schauinsland): These seals grow up to a height of (7-8) feet. These are very good hunters and they have a life span of 25 years. They are found in the waters of Hawaii. They are usually found in groups and are very good swimmers.

Antartic Fur Seal (Arctocephalus gazelle): These seals have a characteristic of living both on land and in water. They like to eat krill, squid and fish. They can grow up to a size of 6 feet in length. They have a life span of (15-25) years.

Galapagos Fur Seal (Arctocephaulus gazelle): These seals are of dark brown to light gray. They feed mostly at night and have a life span of about 20 years.

Northern Fur Seal (Arctocephalus gazelle): These seals have a small nose and thick fur. They feed on any type of fish. They are found in the northern region of Pacific Ocean, the Sea of Okhotsk and Bering Sea. They have a characteristic to live around the shore line most of the time as they are not good divers.

The types of sea given above are interesting to read and know about them. You can read and know about the ecology and behavior of these seals.

Snow Crab

Snow crab (Chionoecetes opilio), has a circular body with five pair of long and flattened legs. They have light brown color on their back and creamy white color on their belly. The male of these species is bigger than the females. They grow up to a size of about (9.5 to 15) cm in length and weigh up to about 350 gm to 1.3 kg. The carapace of these species is as long as wide. The size of the carapace in the males is around 69.3 mm in length and 69.3 mm in width. And the size of the carapace in females is 53.8 mm in length and 54.5 mm in width. They have short pinchers. The meat of this species is very delicious and it turns bright orange when cooked.

Habitat and Distribution

The Chionoecetes opilio is found in the sand and mud. These species are often found in muddy water at a depth of around (13 to 2187) meters. It has been recorded that these species are mostly found at the depth of 110 metes. These creatures occur mainly in the Atlantic Ocean, right from the northern Labrador to the Gulf of Maine. The adults are found throughout the year at the temperature of about (0 to 5) degree Celsius. They can also be found at the temperature of 10 degree Celsius.

Diet

The sea creatures are scavengers and feed on a variety of food. They feed on worms,mollusks, brittle stars and crustaceans.

Life Cycle

The fertilization in these species is internal and the species go through molting before they mate. During mating the male of these species transfer the sperm sac in to the female’s abdomen. The females can have 150000 fertilized eggs in their abdomen. The incubation period in these creatures is around (14 to 16) days. The larvae take two months to grow as a crab. The hatchlings have a danger of being washed away by the tidal high currents of the ocean. Moreover, the hatchlings, which reach to the bottom of the ocean only survive. They live in the ocean floor for sometime till they grow as an adult crab. These species have a life span of around (5 to 6) years.

Ecology and Biology

These Chionoecetes opilio are closely related to the tanner crab, which is found in the cold northern seas. They are popular among commercial species as they have thin exoskeleton. These sea animals are fished by the commercial fishing boats, which are (40 to 250), in length. It has been legally announced that the fishing of these species should be in a limited quantity. The females should not be fished as it may decrease the population of these species.

Snow Crab Recipes

The recipes of these species are very popular among the crab eaters. The meat of these species is very delicious in their taste. So, they are in high demand in the commercial market for restaurants and hotels. The one of the most interesting creature of the sea has one of the tastiest popularity among the crab eaters. 

Isopods

Isopods include animals such as woodlice and pill bugs and belong to the order of Peracarid crustaceans. They are generally small crustaceans and it has seven pairs of legs. It can grow up to a size of (0.0012 to 20) inches. They have a segmented outer shell, which provides protection. Their color ranges from light brown to dark gray or black. In addition, they have cream, white or yellowish spots on their body. It would be interesting to know that about 4500 species of Isopods are found, mostly on the sea floor.

Isopods Behavior

They breathe through gill so they need to be moist at all the times otherwise they will die. It has a characteristic of rolling into tight sphere whenever it feels threatened or stressed.

Isopod Life Cycle and Isopod Reproduction

The female lays several dozen eggs after mating. She carries these eggs in a compact white package between her legs. The egg takes 3 to 4 weeks before hatching. At first, they are nearly invisible but soon they grow to a size that can be seen by the unaided eye. In the molting process, the new shell underneath expands and hardens and the older one casts off. They have a life span of only few years.

Isopod Care and Uses

They can be kept in a 50-liter aquarium. The aquarium is not needed to be covered if the walls are smooth because they cannot climb on the smooth walls. These isopods are fished for the commercial purposes. However, it is also served in the restaurants, which are situated near Oceans in Taiwan. In the restaurants, it is boiled and served with rice.


Isopods Facts

The facts about the isopods are as following:

• Isopods are crustaceans that live on land and in fresh or salty water
• They have gills to breathe
• They need to keep their body moist else they will die
• They can sense the changes in environment
• Most of the isopods live in ocean
• The giant Isopod is the largest in the family

Giant Isopods

The Giant Isopod, is the largest member in the family of the Isopods. It is a group of crustaceans, which is closely related to shrimps and crabs. It is a carnivorous and feeds on bodies of whales, squid and fish. It also feeds on sponges and slow-moving sea cucumbers. These Isopods are found in almost all the oceans of the world. They live generally at a depth of (550 to 7000) feet. The one which lives in deep water grows to a larger size compared to the one which lives in shallow water. These giant isopods can grow up to a size of 16 inches. It has compound eyes and a complex mouth to catch its prey. These giant isopods reproduce by laying eggs, which are thought to be the largest of all the marine invertebrates.

Conclusion
The Isopods are very small and are harmless. They do not bite, smell, jump or fly. They are very easy to care.

Brackish Fish Aquarium

Brackish Fish Aquarium is a type of aquarium which is gaining in popularity however, that is a bit rare. This is the brackish aquarium setup. Most aquarists will easily recognize the "standard" tank types: Freshwater, , Fish-Only-With-Live Rock, Fish-Only Marine and Reef Aquarium.

What is Brackish?

Brackish water is considered to be somewhere between "pure" freshwater and ocean water in salinity. In nature, brackish water is formed by swamps and marshes that are more or less at sea level and on a coast, estuaries, and, rarely, landlocked bodies of water that happen to have salt in them. Brackish water is found all over the world where inland freshwater streams and springs meet the ocean. The lower part of the Hudson River which separates New York and New Jersey is a giant brackish biotope. This is also true for several small canals in sub-tropical Florida. Literally, the word is an adjective to describe any water that is salty or briny. Brackish aquariums have both advantages and disadvantages, when you compare it with freshwater aquarium setup or marine setup. It’s little difficult to keep up compared to a standard freshwater aquarium, but are quite easier compared to a standard marine aquarium. There are some very peaceful species, and there are a few odd species that prefer brackish water. The fish will do fine till the waste products like ammonia, nitrite, and nitrate are all kept at safe levels.

Brackish Tank Setup
One can easily follow the standard freshwater setup for setting a brackish aquarium. For setting up of a brackish aquarium you need to buy aquarium filters that are for either saltwater or freshwater aquariums. Apart from this you also need to buy any other equipment or chemicals you get. The first thing to be noticed where the setup diverges from a standard freshwater tank is, of course, filling the tank. Generally, brackish tank has a specific gravity between 1.005 and 1.010, but it can range anywhere between true freshwater and true saltwater (i.e., up to 1.020). Most of the fish have a preferred specific gravity, but most brackish fish are pretty adaptable in this condition. But it is best to do research and plan according to the gravity requirements. Also, you need a hydrometer to measure the specific gravity. Pay attention to the amount of salt you use. And then, you can follow any of the normal procedures to cycle the aquarium.

What to Stock the Aquarium With?
Some of the common brackish fish are guppies, mollies, gobies, and the dwarf puffer. These are some of the brackish fish. But it’s always better to do research on the fish you are going to keep and then proceed. In addition to fish, there are many invertebrates that live in brackish water. True Amano shrimp, some fiddler, shrimps, crabs, and snails also do well in this type of aquarium. Some plants like Java moss and Java fern can also be kept along with these fish and animals.

Brackish Fish Aquarium Care
Once your aquarium is set up, it is perhaps best to allow the specific gravity to vary periodically. It’s necessary to match the salinity of the new water to that of the old water. Once the fish gets adaptable they can survive up to certain level of changes.