What sponge belongs to the class Hexactinellida?
Glass sponges in the class Hexactinellida are animals commonly found in the deep ocean. Their tissues contain glass-like structural particles, called spicules, that are made of silica (hence their name).
What do Poriferans look like?
Adult sponges can be asymmetrical or radially symmetrical and come in a variety of sizes, colours, and shapes including tree-like, fan-shaped, cup shaped, tube shaped, ball shaped and shapeless.
Where do you find poriferans?
The phylum Porifera comprises the sponges. Sponges are simple invertebrate animals that live in aquatic habitats. Although the majority of sponges are marine, some species live in freshwater lakes and streams. They are found in shallow ocean environments to depths as great as five kilometers (km).
How many Hexactinellida species are there?
The hexactinellids are exclusively marine. Today, the roughly 500 species are mostly known from deeper waters, 200 to 2,000 meters.
What do Poriferans eat?
The Porifera are primarily filter feeders, utilizing food particles suspended in the water and captured by the choanocytes. Food particles consist essentially of bacteria, other microorganisms, and particles of organic debris; sponges also probably absorb dissolved organic substances.
Why are Poriferans called sponges?
The phylum name Porifera means pore-bearing. Sponges take their name from small holes that cover their bodies. The history of life is written on the bodies of the animals that previously inhabited and continue to inhabit earth.
How do Poriferans reproduce?
Porifera reproduce sexually through spawning, or the seasonally triggered release of large numbers of sperm at the same time. The sperm floats through the water and eventually enters a sponge of the same species through a pore, where it is transported to the female eggs.
What is the difference between Hexactinellids and Porifera?
Hexactinellids are widely viewed as an early branch within the Porifera because there are major differences between extant hexactinellids and other sponges. In particular, much of their tissues are syncitia, extensive regions of multinucleate cytoplasm. Some discrete cell types do exist, including archaeocytes.
Where are Hexactinellids found?
Hexactinellids are exclusively marine, and in the modern oceans are usually found at depth (generally 450 to 900 m, but up to 5000 m). Some of the anchoring spicules produced by hexactinellids are extraordinarily large.
Why are hexactinellid sponges So Weird?
The hexactinellid sponges are said to display the syconoid pattern of organization. To put it mildly, this understates the weirdness of the hexactinellid body plan. In fact, hexactinellids have perhaps the strangest of all animal bodies. Most of the tissue consists of a single giant, multinucleate syncytium.
What is the composition of a hexactinellid spicule?
Hexactinellid spicules are produced in concentric layers — up to 500 layers in the case of Monorhaphis. Each layer is thus 10-20 μ thick, composed of small grains of silicate within a matrix of undetermined composition (possibly collagen). The silicate layers are built on a core of amorphous silicate.