Sycon: Unique Marine Organism

Sycon is a marine sponge which is found attached to the rocks, corals and shells of molluscs. Sponges are the members of the phylum porifera. There are approximately 5000 living species of sponges in the world. These are divided into 3 different groups based on the presence or composition of spicules or spongin.

Let us know more about sycon characteristics, its structure, scientific classification,canal system, their nutrition, respiration and nutrition.

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Sycon Classification

The classification of sycon is given below.

• Kingdom: Animalia

• Phylum: Porifera

• Class: Calcarea

• Order: Heterocoela

• Family: Sycettidae

• Genus: Sycon

Understanding the Sycon classification within the broader context of Porifera and Calcarea helps scientists categorize and study its evolutionary relationships, ecological interactions, and anatomical features, contributing to our knowledge of biodiversity and ecosystem dynamics in marine environments.

Geographic Range of Sycon

It is a marine sponge found across the world, generally in shallow water but not more than 150 meters deep. They are predominant. Also, they are commonly found in the arctic ocean, pacific ocean, Indian ocean etc.

Habitat of Sycon

1. Habitat Region -

• Temperature - that region of the Earth between 23.5 degrees North and 60 degrees North. 

• Region - mainly lives in oceans, seas, or other bodies of saltwater.

2. Aquatic Biomes -

• Benthic - Lives at the bottom of a body of water.

• Reef - Reef is the structure produced by the calcium carbonate skeletons of coral polyps.

• Coastal - It is the nearshore aquatic habitat near the coast.

3. Other Habitat Features

• Intertidal or littoral - Littoral is the area of shoreline influenced mainly by the tides.

Structure of Sycon

• Sycon is in the form of branched cylinders, all these branches are attached to the same base.

• Even though the body has firm consistency they are slightly flexible.

• They have minute openings called pores or ostia.

• At the end of each branch it has an opening called an osculum.

• The wall of the sycon is lined by cells called pinacocytes.

T.S of Sycon

• The body wall has two layers: an outer layer and an inner layer.

• The inner layer is made of a mix of cells and tiny structures, with flat cells lining its inside.

• The outer layer is also made of flat cells and has tiny holes called ostia.

• These holes lead to channels that bring in water, which then goes through smaller channels lined with special cells.

• These channels lead to even smaller ones, lined with more flat cells.

• Eventually, all these channels open up into a central cavity.

• The whole system is called a syconoid canal system.

Characteristics of Sycon

• The length of the sycons vary from 2.5cms to 7.6cms. 

• Their bodies are radially symmetrical or asymmetrical.

• They have the capability to regenerate their lost parts.

• Needle-like spines called spicules cover their body.

Canal System of Sycon

The body of the sycon contains pores and canals which results in the formation of a canal system of sycon. This canal system is used to draw watercurrent inside the body. The food and oxygen is transported inside the body through the water current.

The composition of canal system of sycon is as follows:

• Ostia: The pores present on the body of the sycon are called ostia. It sends the water current into the incurrent canals. It also regulates the amount of water entering the body.

• Incurrent Canals: The dermal pores send water to the incurrent canal which is narrow from inside. These are lined by pinacocytes. The inner end of the canal is closed. There is a presence of small apertures called prosopyles in between the incurrent canal and radial canal. 

• Prosopyles: The prosopyles help to move the water inside the radial canal.

• Radial Canals: The radial canal is lined up by choanocytes or flattened cells. These choanocytes help to move the water inside the body. These are closed externally and opened by a small aperture called apopyle.

• Apopyle: The connection between the radial canal and the excurrent canal is called apopyle. These are surrounded by myocytes.

• Excurrent Canal: The excurrent canal is lined by pinacocytes. This canal connected to the spongocoel through an opening called gastric ostium.

• Spongocoel: Spongocoel is a narrow cavity lined by pinacocytes. It opens out through the osculum.

Microscopic Organization

In simple terms, when we look at things really closely, we see that there's a thin layer covering the outside made of tiny cells. This layer is called the dermal layer, and it's where small needle-like structures called spicules come from. This layer has big cells called pinacocytes.

Inside, there is a space called the spongocoel which has a lining made of flat cells. The radial canal, another part inside, is lined with special cells called collar cells or choanocytes. These cells have a long whip-like structure called a flagellum. Each choanocyte is oval or round and has little pouches inside it. At one end, there's a longer whip-like structure, and around its base, there are some see-through projections that can squeeze.

The flagellum comes out from a tiny dot called a basal granule connected to something called a rhizoplast. The see-through projections are made up of some tentacles made of jelly-like stuff. There are usually around 20 to 30 of these tentacles.

The skeleton of this thing called Sycon is made up of those spiky things we talked about earlier, which come from something called scleroblasts. They're arranged in a way to protect the delicate parts. You might see these spiky things in shapes like four lines or three lines spreading out.

In the gel-like stuff inside this thing, there are different types of cells floating around:

• Collenocytes

• Myocytes

• Thesocytes

• Archaeocytes

• Gland Cells

• Chromocytes

Sycon Reproduction

In sycon reproduction we can observe both sexual and asexual modes.

• In asexual mode they produce buds and in some cases it produces special structures called gemmules.

• In sexual mode, the female gametes and male gametes are produced from the archaeocytes present in mesoglea. The sperm cells have long tails and can swim freely in the water current. The ova can wander in mesoglea.

• The sperm cell does not enter the ova directly. But the sperm moves nearer to the egg by the assistance of the choanocyte. 

• The early development is seen inside the mother sponge. When the development is complete, it is moved to a radial canal and from there it emerges.

Sycon Respiration

The sycon respiration is carried out by a simple diffusion process.

• This diffusion causes the exchange of gasses in between sponge cells and the water.

• The oxygen is dissolved in the water and is diffused into the cells. This diffusion causes oxidation of protoplasmic molecules with the release of energy in the form of ATP.

Sycon Nutrition

• Sponges get their food from tiny organisms brought in by water currents.

• These organisms enter the sponge through small openings called Ostia.

• Sponges eat by filtering out tiny particles like plankton and other organic matter from the water.

• Inside the sponge, there are special cells called choanocytes that catch and pass food to other cells for digestion.

• The digestion process happens inside these cells, and the nutrients are then sent to different parts of the sponge.

• Some cells in the sponge also contain chlorophyll, which helps them make their own food.

• Water enters the sponge through chambers lined with cells that have flagella or collar-like structures.

• As water flows through these chambers, food particles get stuck to the collars of the cells.

• These cells have tiny hair-like structures called microvilli that act as filters to trap food.

• The trapped food particles are then taken into food vacuoles for digestion.

• The digestion process starts with acidic conditions and then becomes alkaline.

• After partial digestion, the food is passed to other cells called amoebocytes, which move around the sponge.

• Amoebocytes complete the digestion process and then distribute the nutrients to other cells.

• Some nutrients are stored for later use.

• Enzymes that help digest fats, starch, and proteins are also produced by these cells.

• Finally, the waste products are expelled out of the sponge through outgoing water currents.

Current of Water in Sycon

The flow of water in sycon is maintained by continuous flagellar beating of choanocytes. So, the water rushes along the external surface and enters inside the body through many tiny holes called Ostia on the outside. Then, it moves through the incurrent canal and into the radial canal via prosopyle. Next, it flows into the spongocoel through apopyles. The spongocoel acts as a central chamber where all the radial canals connect.

Eventually, water exits through the osculum, which is one big opening. So, while water comes in through lots of Ostia, it leaves through just one osculum. Inside the radial canals, choanocytes with flagella create currents that both pull water in and push it out.

Function of water current in this sponge:

• By means of this current,  exchanges between the sponge body and the external medium takes place.

• With the help of this water current, food and oxygen is brought into the body.

• The excreta is taken out of the body by the water current.

• The water current carries out the reproductive bodies into the body of the sponges .

Answer the following MCQs:

(i) A sycon is a type of marine ______.

(a) plant

(b) sponge

(c) rock

(d) chemical

Ans: (b) it is a type of marine sponge.

(ii) Which of the following sponge is found in the river?

(a) Cliona

(b) Sycon 

(c) Spongilla

(d) Hyalonema

Ans: c) Spongilla

(iii) Sycon belongs to which of the following groups of animals?

(a) multicellular organisms without any tissue organization

(b) multicellular organisms and which a gastrovascular system

(c) multicellular organisms which have tissue organization, but have no body cavity.

(d) unicellular organisms or acellular organisms

Ans: (a)  multicellular organisms without any tissue organization

Answer the following :

(i) What is sycon ciliatum?

(ii) List out the points of differences between sycon and hydra.

Answer: 

(i) Sycon ciliatum is a sycon species (calcareous sponge) which belongs to the family Sycettidaephylum.

 It's specification are:

• Kingdom - Animalia

• Phylum - Porifera

• Class - Calcarea

• Order - Leucosolenida

• Family - Sycettidae

• Genus - Sycon

• Species - S. ciliatum

It is a type of small purse sponge which grows singly or in a small group from single holdfast. It's length is upto 5 centimeter. It has a covering of fine papillae on its surface. This gives it the furry look. It's skeleton consists of tangential layers of triactines and tetractines. This specie is different from the other species because in this, the choanocyte chambers are free from each other and are not fused. It is commonly found along the coasts of Europe and also seen on the eastern fringes of the Atlantic Ocean.

(ii) Sycon and hydra differ from each other in the following ways:

• Sycon belongs to the phylum Porifera (which shows cellular level organization) whereas Hydra belongs to the phylum Coelenterata (which has tissue-level organization).

• Sycons are asymmetric whereas hydra are radially symmetric.

• Sycons are mostly marine animals (few of them are also freshwater organisms) but Hydra is always a freshwater organism.

• Sycons eat tiny organic particles that float in the water flow. Hydra are carnivorous and eat small insects and the insects with larvae. 

• Sycons do not have a mouth whereas hydra have a mouth. 

• Sycons are found deeper than the hydra plants.

Conclusion

Sycon, a type of sponge, features a unique canal system that facilitates water flow for feeding and waste removal. Its classification places it within the phylum Porifera. Key characteristics include its asymmetrical body, composed of choanocyte-lined canals, and spicules for support. Understanding its structure is crucial for grasping its ecological role. Focus should center on comprehending its canal system's efficiency in nutrient intake and waste expulsion, its role in marine ecosystems, and its significance in evolutionary biology. By delving into these aspects, researchers gain insights into Sycon's contribution to marine biodiversity and potential applications in fields like biotechnology.