Aquarium Biology Guide PDF

# Alkalinity - Buffering Capacity - Alkalinity refers to the ability to buffer against fluctuations in pH. - Alkalinity is provided in the aquarium by negatively charged ions: - Carbonates - Bicarbonates - Borates - Hydroxides - **Carbonate Hardness** is a term sometimes used interc...

# Alkalinity - Buffering Capacity - Alkalinity refers to the ability to buffer against fluctuations in pH. - Alkalinity is provided in the aquarium by negatively charged ions: - Carbonates - Bicarbonates - Borates - Hydroxides - **Carbonate Hardness** is a term sometimes used interchangeably with alkalinity but it only describes the amount of carbonate and bicarbonate dissolved in the water. - Borates and hydroxides also contribute to alkalinity. # Phosphate - Phosphates accumulate in aquarium water over time. - Phosphates can negatively affect the health of invertebrates. - They come from: - Digestion of food by aquarium animals - Decay of excess food - Some activated carbon products - **Overfeeding** is the main cause of increased phosphate concentrations. - Water changes and phosphate removing products can be used to remove phosphates. - Phosphate can be present in organic and inorganic forms and not all testing equipment measures both. # Salinity - Salinity is applicable only to marine aquariums. - It is the ratio of dissolved salt in the water compared to pure water. - Pure water has a specific gravity of 1.00. - Marine aquariums should have a specific gravity ratio of 1.018 to 1.025. - A hydrometer measures specific gravity. - It is important to consider water temperature when taking a salinity reading because some hydrometers are temperature dependant. # Fish Reproduction - Fish reproductive organs include testes and ovaries. - These are paired organs that may be partially or totally fused. - Secondary organs can increase reproductive fitness. - The **genital papilla** is a small, fleshy tube behind the anus of some fishes. - Sperm or eggs are released from here. - The sex of the fish can often be determined by the shape of the papilla. # Lion Fish # Clown Trigger Fish # Ornamental Fishes ## Marine Mollusk - Nautilus pompilius - Murex sp. # Mussel Anatomy # Cnidarians - Sea Anemone - Soft Corals # Marine Sponges # Marine Crustaceans ## Marine Zooplankton - Copepod # Echinoderms ## Anatomy of Starfish ## Distribution and Abundance - Diverse echinoderm faunas consisting of many individuals and many species are found in all marine waters except the Arctic, where few species occur. - Echinoids (including globular spiny urchins and flattened sand dollars) and asteroids are commonly found along the seashore. - While many species are restricted to specific temperate regions (Arctic, Antarctic and tropical forms) some species are widely distributed. - For example, many species associated with coral reefs range across the entire Indian and Pacific oceans. - Many echinoderms of Antartica are distributed around the continent; those with a floating (planktonic) larval stage may be widely distributed, carried great distances by ocean currents. - Some species (particularly those in Antarctic and deep-sea regions) have achieved a wide distribution without a floating larval stage. - They may have achieved this by migration of adults across the seafloor. - Or by passive transport across oceans in rafts of seaweed (shallow-water species only). - Echinoderms tend to have a fairly limited depth range. - Species occurring in near-shore environments do not normally reach depths greater than 100 metres. - Some deep-sea species may be found over a considerable range of depths (often from 1,000 metres to more than 5,000 metres). - One sea cucumber species has a known range of 37-5,205 metres. - Only sea cucumbers reach ocean depths of 10,000 metres and more. ## Reproduction and Life Cycle - In most species, the sexes are separate (males and females). - Reproduction is usually sexual (involving fertilization of eggs by spermatozoa). - Several species of sea cucumbers, starfishes, and brittle stars can also reproduce asexually. ### Asexual Reproduction - Asexual reproduction in echinoderms usually involves the division of the body into two or more parts (fragmentation) and the regeneration of missing body parts. - Fragmentation is a common method of reproduction used by some species of asteroids, ophiuroids, and holothurians. - Some of these species do not exhibit sexual reproduction. - Successful fragmentation and regeneration require a body wall that can be torn and an ability to seal resultant wounds. - In some asteroids, fragmentation occurs when two groups of arms pull in opposite directions, thereby tearing the animal into two pieces. - Successful regeneration requires that certain body parts be present in the lost pieces. - For example, many asteroids and ophiuroids can regenerate a lost portion only if some part of the disk is present. - In sea cucumbers, which divide transversely, considerable reorganization of tissues occurs in both regenerating parts. ### Asexual Reproduction - The ability to regenerate, or regrow, lost or destroyed parts is well developed in echinoderms, especially sea lilies, starfishes, and brittle stars, all of which can regenerate new arms if existing ones are broken off. - Echinoderm regeneration frustrated early attempts to keep starfishes from destroying oyster beds. - When captured starfishes were chopped into pieces and thrown back into the sea, they actually increased in numbers. - As long as a portion of a body, or disk, remained associated with an arm, new starfishes regenerated. - Some sea cucumbers can expel their internal organs (autoeviscerate) under certain conditions. - When attacked - When the environment is unfavourable - On a seasonal basis - A new set of internal organs regenerates within several weeks. - Sea urchins (Echinoidea) readily regenerate lost spines, pincerlike organs called pedicellariae, and small areas of the internal skeleton, or test. ### Sexual Reproduction - In sexual reproduction, eggs (up to several million) from females and spermatozoa from males are shed into the water (spawning), where the eggs are fertilized. - Most echinoderms spawn on an annual cycle, with the spawning period normally lasting one or two months during spring or summer. - Several species, however, are capable of spawning throughout the year. - Spawn-inducing factors are complex and may include external influences such as temperature, light, or salinity of the water. - In the case of one Japanese feather star (Crinoidea), spawning is correlated with phases of the Moon and takes place during early October when the Moon is in the first or last quarter. - Many echinoderms aggregate before spawning, thus increasing the probability of fertilization of eggs. - Some also display a characteristic behaviour during the spawning process. - Some asteroids and ophiuroids raise the centre of the body off the seafloor. - Holothurians may raise the front end of the body and wave it about. - These movements are presumably intended to prevent eggs and sperm from becoming entrapped in the sediment.