Sponges and Cnidarians

WELCOME!!

The sea is inhabited by a large number of animal species. They range from microscopic worms to giant squids. Regardless of their size each fills a particular niche in the overall marine ecosystem.

What are animals?

1. Animals are multicellular.

2. Animals are eukaryotic.

3. Animals cannot produce their own food, so they depend on other organisms for nutrients. They are heterotrophs.

4. Animals, with the exception of adult sponges can actively move.

Animals that lack vertebral column are invertebrates, whereas animals that have a vertebral column are vertebrates.

Sponges- are simple, asymmetrical, sessile animals (meaning they are permanently attached to a solid surface.) Sponged exhibit a wide variety of sizes and shapes, and their shape is frequently determined by the shape of the bottom, or material on which they grow and by the water current.

Although many living sponges are a drab, some species are brightly colored. Red, yellow, green, orange and purple are common

A Sponges body is unique in that it is built around a system of water canals because of the sponged sessile lifestyle. Their bodies are full of tiny holes, or pores called ostia through which large amounts of water circulate.

Because sponges feed on material that is suspended in seawater, they are called suspension feeders or filter feeders because they filter their food from the water.

Sponges can reproduce both sexually and asexually. Asexual reproduction can either be budding or fragmentation.

Although they are simple sessile animals, sponges interact with other marine organisms in several ways. They compete for space. They are links in some marine food chains. Sponges form many symbiotic relationships and they provide habitat for other animals.

Cnidarians: Animals with stinging cells

Cnidarians are a group of animals that consist of hydroids, corals, sea anemones and jellyfish.

Cnidarians have bodies that exhibit radial symmetry . This means that many planes can be drawn through the central axis that will divide the animal into two equivalent halves.

Cnidarians can reproduce both sexually and asexually.

One of the most important features of cnidarians is their stinging cells(cnidocytes). The stinging cell contains a stinging organelle called cnida.

Many species of cnidarian such as the Portugese man-of-war can cause painful stings.

The stings of a box jellyfish can be fatal

Types of Cnidarians:

Hydrozoans- or hydroids, composed of individuals that are physically connected to share resources like food.

Jellyfish and Box Jellyfish- most jellyfish float with the currents and are not strong swimmers. They have photorecptors that allow them to determine if its dark or light out.

Anthozoans- Sean anemones, corals and gorgonians. Benthic animals and all adults are sessile.

http://www.youtube.com/watch?v=eyCigZ_bsTM Here is video from National Geographic called Jellyfish Invasion!

"Sea" you real soon!