Sponges in Sea and oceans

Calcareous sponges are largely confined to the littoral and the shallow seas, although a few have been dredged at depths down to 600 ft. or beyond, to a maximum depth of 2,700 ft. Hexactinellida is typically deep-sea, the majority of species living at depths greater than 600 ft., but around the Indo-Pacific islands they seem … Read more

Sponges Skeleton and spicules

With few exceptions, the body of a sponge is supported by a skeleton made up either of spongin fibers, usually forming a network, as in the bath sponges (Spongia), or of spicules (little spikes) of silica or carbonate of lime. Although we speak of the spicules as constituting a skeleton there are some remarkable differences … Read more

Reproduction in sponges [Phylum Parazoa]

Reproduction in sponges [Phylum Parazoa] This is by both sexual and a variety of non-sexual methods. All sponges appear to bear both ova and spermatozoa, although there has recently been a suggestion that this is not invariable, and fertilization may be internal or external. With internal fertilization the embryos develop inside the sponge, which is … Read more

Protozoa Gymnostomes, Order Gymnostomatida, Rhabdophorina, Cyrtophorina, Suctorida

Gymnostomes (Order Gymnostomatida) – Protozoans As the name suggests the mouth is without ciliary organelles. This is a most diverse group of structurally simple ciliates. But diversity has led to considerable changes in classification in recent years. A comparison of current classifications shows that no general agreement has yet been reached. Most species in the … Read more

Ciliates Classes : Ciliata, Holotricha

Ciliates (Class Ciliata) – Protozoans These protozoans have many cilia and nuclei of two sizes. Because the mastigophoran Opalina also has many flagella (or cilia), it is the nuclei that act as the criterion and establish the true ciliates as a distinct group. Other features include a kinety. Holotrichs (Subclass Holotricha) This group is regarded … Read more

Protozoa Subclass Coccidiomo

Protozoa Subclass Coccidiomo Subclass Coccidiomo This group is distinguished from the previous one by spending the whole of its trophozoite life intracellularly, and by effecting massive reproduction with schizogony. There is only one major order which contains three suborders. These are markedly different from one another. Order Eucoccidia These are parasites of epithelial cells of … Read more

Protozoa Subclass Gregarinomorpha 

Subclass Gregarinomorpha In this group are placed various parasites with reproductive similarities. The trophozoite is large and feeds in the lumen of the host’s gut or between cells Genetic exchange is achieved by a union of two sporonts (mature trophozoites) prior to gametogenesis. This union and the formation of gametocysts ensures that gametes can find … Read more

Sponges Phylum Parazoa examples Characteristics and Orders

All sponges are aquatic and most of them are marine. Where Freshwater sponges exist? Freshwater sponges are found in fair numbers—but belonging to relatively few species—in ponds and lakes, streams and rivers, even in lakes formed in the craters of extinct volcanoes 10,000 feet above sea-level. Where Marine sponges exist? Marine sponges exist in large … Read more