Identify this tuber like object found on beach

Can anyone identify this tuber-like object I found on a beach in South Wales, UK? It's about 25 cm long and looks like a deflated football. Pretty spongy, saturated with water. I was hoping it was ambergris, but that seems unlikely.

It is spongy because it is a sponge, specifically a sea sponge. There are quite a large number of them native to the waters around england. I would guess Craniella cranium based on shape and location but I am by no means an expert on sponges. Here a cross section of a cleaned sponge

and sediment laden potato sponges after a hurricane.

you can see more images of collecting these here,

Here is a whole website dedicated to english sea sponges,

Identify this tuber like object found on beach - Biology

Marine Worms

We tend to think of those pink (often dead) worms in our garden when we think of worms, but they're on the beach too - and looking very different.

Don't sue me if you don't actually see a worm though - what you are more like to see is signs that a worm is around, rather than the actual worm itself.

Sea Mouse or Aphrodita

The sea mouse is a type of polychaete worm (segmented, bristly worms) known as a scaleworm that can grow up to 30 centimetres long but are more usually around 10 or 15 centimetres in length. They feed on small crabs and hermit crabs and other worms. To warn off predators, they are covered in bristles which can flash green, blue or red.

They are common all round the coast of Britain but not found very often.

Lynn Martin found the sea mouse pictured in Westward Ho!.

Ragworms are more commonly found in rockpools than when beachcombing but as this one turned up in a whelk shell I picked up on the strandline, I thought it deserved a place here. Another form of polychaete worm (see sea mouse above), ragworms like to hide in shells, under stones, and in silty sand, They forage for whatever they can find to eat - plant or animal, they are not fussy. Called ragworms as they go completely limp if picked up.

Live Rock Hitchhikers

The introduction of Live Rock is the single best way to increase the biodiversity of your aquarium. The goal is to try to obtain a balance and to match that which is found in nature. In the past, the word “hitchhiker” came with a negative connotation. We have come a long way in the hobby and the term hitchhiker is now used to describe the vast array of life of Live Rock hitchhikers. Nearly all of these creatures will add to the balance of life found in your tank.

The Beneficial Roles of Live Rock Hitchhikers:

  • Processing of waste and detritus.
  • Filtering your tanks water.
  • Stirring and oxygenating your sand-bed.
  • Keeping nuisance algae at bay.

99% of these hitchhikers and reef critters are a valuable addition to your aquarium. This species identification guide will cover all these beneficial critters as well as the 1% that make up the bad hitchhikers and reef tank pests, as well as how to easily remove one should you be part of that 1% who get a hitchhiker pest that is not beneficial. This guide may help identify hitchhikers from other types of Live Rock but it is meant to be specific to ARC Reef Live Rock and ARC Reef Premium Live Rock, both of which are 100% aquacultured and harvested from the Atlantic Ocean. If you have purchased our Live Rock and found a hitchhiker not listed feel free to Contact Us or call us at 1 (800) 268-ROCK and we’ll help you to identify that particular species of hitchhiker. If you are looking to avoid all saltwater aquarium pests then the best alternative method is to purchase Dry Rock and then to add Coralline Algae to your tank via one of our Coralline Algae Starter Packages . All coralline algae packages come with the beneficial bacteria that your new dry rocks will need to be successful. Click here for Coralline Algae for Sale .

Identification of Bacteria: 7 Steps

The following points highlight the seven steps for identification of bacteria isolated from a specimen. The steps are: 1. Morphology and Staining 2. Cultural Characteristics 3. Biochemical Reactions 4. Antigenic Characters 5. Typing of Bacteria: Bacteriophage Sensitivity 6. Animal Pathogen City 7. Antibiotic Sensitivity.

Identification of Bacteria: Step # 1. Morphology and Staining:

Serve as preliminary criteria. The Gram stained smear shows the Gram reaction, size, shape, groupings of the bacteria and intracellular position of the endospore. Special staining reaction can reveal the presence of capsule.

Hanging drop wet preparation can be used to study the motility of bacteria. An unstained wet film is examined under dark ground illumination microscope to observe the exact morphology of delicate spirochaete. A smear is stained by Ziehl Neelsen method to demonstrate the acid fast staining reaction.

Identification of Bacteria: Step # 2. Cultural Characteristics:

The growth requirement and the appearance of colonies on media to the naked eye are further criteria to assist the identification of bacteria. A culture is a growth of bacterium on artificial nutrient medium or culture medium prepared in the laboratory.

Attempts are made to grow (to cultivate or culture) the bacteria on media of different compositions (glucose, inorganic salts mixture, meat extract or meat infusion with blood) incubated under a variety of conditions (different temperatures, pH) in the presence of atmospheric oxygen (aerobically).

The ability or inability to grow on medium containing a selective inhibitor (e.g. bile salt, optochin, tellurite, bacitracin, malachite green, low pH, high pH) may also be useful to identify the bacteria.

The growth of bacteria in liquid culture medium (e.g. nutrient broth) may show:

(2) Little deposit at the bottom

(3) Surface growth (pellicle formation). (Fig. 7.1a).

The appearance of the discrete masses of growth or colonies that can be grown from isolated bacteria on the surface of the solid medium (nutrient agar) can be used to study the size of the colonies (diameter in mm), their outline (whether circular, entire, indented or wavy or rhizoid), their elevation (low convex, high convex, flat, plateau-like, umbonate, or nodular)—Fig. 7.1b), their transparency (clear and transparent) or opaque, whether they are colourless (white or pigmented) or whether they produce any change in the medium (e.g. haemolysis in the blood agar medium).

Identification of Bacteria: Step # 3. Biochemical Reactions:

E.g. fermentation of various sugars (carbohydrates). Morphology and cultural characters may not be able to distinguish some species of bacteria but these same species may exhibit distinct differences in their biochemical reactions e.g. typhoid and paratyphoid bacilli (glucose and mannitol are fermented without gas production by typhoid bacilli, whereas paratyphoid bacilli produce acid and gas).

Certain serotypes of the salmonella group may resemble one another in fermentation properties.

The growth of the bacteria in liquid medium will ferment particular sugars (glucose, lactose, mannitol) with the production of acid, which is detected by the changes of colour of Andrade’s indicator dye incorporated in the medium the gas production is detected by the collection of air bubble in a small inverted tube (Durham’s tube) immersed in the medium.

Other tests are used to find out the ability of a bacterium to produce particular end products e.g Indole, hydrogen sulphide, nitrite and certain enzymes (oxidase, catalase, urease, gelatinase, collagenase, lecithinase, lipase) in culture media.

Identification of Bacteria: Step # 4. Antigenic Characters:

Species or types of bacteria can be easily and distinctly identified by “specific” antibody reactions observed in serological tests performed on a glass slide. This specific antibody (antiserum) is obtained from the animal (rabbit) immunized against a particular type of microorganisms which agglutinates with the same antiserum.

An unknown bacterium may thus be identified by demonstrating its reaction with one out of a number of standard known antisera.

Similarly, the serum of a person suffering from a bacterial infection may contain specific antibody. The nature of the infection may thus be diagnosed by demonstrating that the patient’s serum agglutinates one out of a number of known antigens of laboratory cultures, e.g. Widal test in Typhoid fever.

Identification of Bacteria: Step # 5. Typing of Bacteria: Bacteriophage Sensitivity:

A single bacterial pathogenic species may include different types of strains which are distinguishable in minor characters. Recognition of the type of a strain isolated from a patient may be of great importance in epidemiological studies related to the source and the spread of the infection in the community.

The typing of stains may be done by special biochemical or serological tests. Another important method of typing is by testing the susceptibility of the culture to lysis by each of a set of type specific, lytic bacteriophages.

Identification of Bacteria: Step # 6. Animal Pathogen City:

Final identification of a toxigenic strain of tetanus bacillus may be done by injecting the toxin liberated by tetanus bacillus into the base of the tail of two mice, one of them has already been protected by prior injection of specific antiserum to tetanus toxin (a soluble poisonous protein secreted by the tetanus bacilli).

The unprotected mouse shows the symptoms of tetanus, whereas the protected one without any tetanus symptoms identifies the culture, as an organism producing toxin, as the injected antiserum neutralized toxin liberated by tetanus bacilli. Similarly, diphtheria bacillus is also identified by inflammation and necrosis of the skin of guinea pig brought by diphtheria exotoxin.

Identification of Bacteria: Step # 7. Antibiotic Sensitivity:

The organism is tested for its ability to grow on artificial nutrient media containing different antibiotics and chemotherapeutic agents in different concentrations. In disk diffusion test, the culture to be examined is inoculated confluently with swabs over the surface of an agar plate and six to ten paper disks containing different antibiotics are placed in different areas of the plate.

Antibiotic diffuses outwards from each disk into surrounding agar. On incubation, the bacteria grow on areas of the plate except those around the antibiotic disks to which they are sensitive. The width of each growth-free “zone of inhibition” is a measure of the degree of the sensitivity of the drug.

Information about the sensitivity patterns of strains (anti-bio-grams) isolated from the patient is required as a guide to the drug of choice for therapy and may also be used as an epidemiological marker in tracking hospital cross-infection.

Learning About Mollusks And Their Shells

As we read about the Phylum Mollusca together, the kids started automatically sorting the shells into groups (or classes) – bivalves, gastropods and cephalopods.

Gastropods are the largest classes of mollusks. This class includes snails, slugs, whelks, and conches. Most gastropod shells have visible growth lines. The kids immediately made the connection to the growth lines of trees. Making connections like these help kids understand concepts rather than simply memorizing facts.

The fact that Class Cephalopoda contains the organisms that make the spiral shells we found AND octopus and squid amazed the kids!

As the kids examined at the bivalve shells we got from the beach, my daughter noticed that they were just like the fresh water mussels we see in my parents lake. “They are the same! We have bivalves in Illinois, too!” I love light bulb moments.


on August 17, 2010 at 8:27 pm

I never knew they came in different colors. My sister and I went to Sanibel with my 2 youngest a while back, they found this huge pinkish tan blob that we later found out was sea pork. I took a pic of it too, I’d be ok not finding any again :)

LOL! You come up with the best “stuff”!

I was in Fort Myers Beach/Sanibel in early August . . . have tons of pictures of these “blobs” . . . had no idea what they were . . . glad to be educated.

I have always wondered about these things – thanks!

Hi Pam…too bizarre! I will have to show this to Fritz, He will be a fan. Lol. He likes any kind of pork…bacon, sausage, yuk:) You Do come up with some Very cool stuff! I’m going to have to start looking for this! Miss you!

When I did a little research on this sea pork to get my facts straight, the wiki/encyclopedia/dictionary sites all had ads for recipes and cookbooks. LOL Warning, Warning….. Sea Pork can be dangerous to your health if consumed. haha (actually, I really don’t know if it is dangerous but I’M NOT gonna try it to find out!)

Amen, Sista…no way will that particular item make it on my table, EVER! EEEEEEWW!

I can think of lots of things I’d venture to taste for the first time — sea pork has no chance of making the list! Thanks for all the great info, Pam!

I think the name “sea pork” makes it sounds more gross than it actually is. I saw a couple of things while there in July – I thought they were some kind of jelly. Thanks for the education.

All your info is so amazing!! And I’m throwing my hands up in surrender….I’ve been to many caribbean beaches and thought I’d seen so many shell islands, but nah. I’ve never seen the amount and different kinds of shells that you guys find where you are!!
I have got to come to your neck of the woods soon!!

I bet….as gross as it is… either poked it with your finger…or your toe…or both. I did!! = ) (Kinda like a wet paint sign!)

Yes! LOL of course I had to.

great new info!! thanks again

If the sea pork contains a group of organisms does anyone know whether it is dead or alive when it washes up on the beach ? Should we be throwing it back in? My son gathered up a ton of it and put it together then took was beautiful actually…but the question is, did he then harm all those tiny guys?

We found a huge one on the north side of Captiva just a few days ago. (Mar. 2012) It was covered except for the size of a quarter but had seaweed on the top so I thought it was a carrot that had been buried. As we started digging it up, it was about 10 lbs and a foot by a foot by 4″. We had no idea what it was. Thanks for the information.

Thank you so much for identifying ” sea pork brainy” . I saw lots of this on the beach of Oak Island, NC during a recent visit. I did several web searches to no avail. Now I know what it is.Love your site.

Found it at Cape Elizabeth in Portland, Maine

I saw all of those except the black and brainy. Still have few days left, so maybe!
I can’t believe all the sea items I have found and either taken or photographed. SO much fun. We live on Cape Cod in the summer and have seen nothing like this.
Wondering what the various shades of orange, soft stuff that looks like coral, is and can it be preserved.

very interesting! I wondered what this alien-looking creature was for the last 3 years here vacationing each January at Redington Shores. Thanks for the info! We mostly get it washing up in the grey and orange colours!

Me and my family went to marco island this spring break. We were playing in the water and all of the sudden this weird purple blob thing washes up on the beach! We weren’t sure what is was so we kept it on our hotel deck to try and dry it out. Later that day it started raining and it was our last day. My family told me to put Fred back (I named him Fred) so I did. I never knew what he was until now so thanks I have been VERY curious, BELIEVE ME.

Cool! Wondering what it was! I thought maybe it was a colony of Red Tide? or possibly some marine life organ.
Found some of this at Coquina Beach Fl. today! One colony was about 8 inches diameter!
(Today is Monday, had Bad storm and tornado(s) here Sunday morning. (Winds and surf still higher today.)
I didn’t have a stick to poke it with (j/k) so felt it. Pliable hard/soft rubbery feel. Pretty color pink. Had whitish coral type circles within it’s membrane. Hehehe! I did think about the blob lol! Thank you for posting this and letting us know! Wish I had taken pictures of it!

There was a lot of it today at North Myrtle Beach! I thought it was super weird! Weird enough that I googled “What’s that pink glob on the beach?” It was the color of shrimp when cooked, sort of pink, white, and red marks.

List of 3 Common Saprophytic Fungus (With Diagram)

List of three common saprophytic fungus: 1. Mucor 2. Yeast 3. Penicillium.

Saprophytic Fungus # 1. Mucor:

Mucor, also called mould, is a very common saprophytic fungus growing abundantly on decayed organic matters, parti­cularly on those rich in carbohydrates—starch and sugar. Soft white cottony patches of Mucor are frequently found on rotten bread, vegetables and dung.

Plant Body:

The plant body is a copiously branched mycelium, which is a collection of slender non-septate threads called hyphae (sing, hypha). The wall, made, of fungus-cellulose, enclose cytoplasm with many vacuoles and innu­merable nuclei (Fig. 192).

So they are coenocytic. Glycogen and oil globules are present to serve as reserve food. The hyphae become thinner and thinner, the more they penetrate into the sub­stratum for absorbing nourishment. Non-septate mycelium becomes septate on attaining old age and during reproduction.


Mucor is reproduced by asexual and sexual methods. During asexual reproduction a number of stout aerial hyphae shoot up from the superficial mycelium. After growing to a certain extent, the tip of each of them swells, and some protoplasm with reserve food flows to the enlargement from the adjoining region. Proto­plasm collects more densely towards periphery, the central portion remaining comparatively thin and vacuolated.

A good number of vacuoles arrange themselves between the outer denser protoplasm, called sporoplasm, and the central thinner protoplasm, known as columella-plasm.

The flattened vacuoles coalesce, and as a result, a distinct cleft is formed separating the two regions now a wall is constructed along the cleft delimiting the central sterile dome-shaped region, called columella, which projects into the enlarge­ment. By progressive cleavage or furrowing the sporoplasm now breaks up into a good number of angular masses, each with cytoplasm and many nuclei.

They round off, tough black walls are secreted and final­ly become spores. Mucor spores are also called gonidia (sing, gonidium). The en­largement containing the spores is the sporangium or gonidangium, and the hypha bearing the sporangium at the tip is called sporangiophore or gonidangiophore (Fig. 193).

The outer wall of the sporangium dis­solves in water and the spores are libera­ted. Often a number of spores remain held in suspension. On suitable medium each spore germinates forming one or more germ tube which gives rise to new mycelium.

Sexual reproduction in Mucor takes place by conjugation. Usually hyphae of two sexually different strains, designated as + strain and — strain, send out club-shaped branches called pro-gametangia, which touch at the tips.

Terminal portion of each branch swells and is cut off by a transverse septum. The compart­ments thus formed, function as gametangia, and their protoplasmic contents as gametes. The gametes here are multinucleate and hence called coenogametes.

The remaining portion of hyphal branch is known as suspensor. On dissolution of the wall between them, the gametes fuse, cytoplasm with cytoplasm and nuclei with nuclei in pairs. The nuclei which do not fuse in pairs ultimately disintegrate.

The zygote (zygospore) thus formed enlarges and secretes a tough wall around it which is often warty or spiny. After a period of rest it germinates, when the outer wall bursts and the inner wall with the protoplasmic contents comes out as an un-branched tube (Fig. 194). This is called promycelium.

Tip O promycelium enlarges and produces spores, each of which can give rise to a new mycelium. The spores produced in the sporan­gium resulting from the germination of a zygospore are either all + or all —, never both.

Though Mucor produces isogametes, it shows distinct differen­tiation of sex. American botanist Blakslee showed in 1904 that zygote formation in Mucor is possible only when gametes pro­duced by two different strains meet.

He termed them as + strain and — strain, rather than male and female for the two mycelial types- Morphologically, there is not much difference between the two, only + mycelium grows a bit more vigorously than its — counter­part.

Such species are called heterothallic. Parthenogenesis is not uncommon in this fungus. One of the gametes may behave like a zygospore without actual pairing. This is called azygospore or parthenospore.

Yeast condition or Torula stage of Mucor:

If a portion of non-septate mycelium is put in sugar solution, it readily develops septa and finally breaks up into many one- celled parts called oidia. Like yeast, oidia multiply by budding and can also excite alcoholic fermentation in sugar solution. This is yeast condition or torula stage of Mucor.

Saprophytic Fungus # 2. Yeast (Saccharomyces):

Yeast is a common saprophytic fungus growing in sugary substances. They are abundantly present in grape juice, vine­-yards, nectaries of flowers and sugary exudates of plants like date- palm, juice and palmyra-palm juice.

Plant Body:

The plant body is very simple. Yeasts are unicellular organ­isms. Each cell is elliptical or round in shape having a distinct cell wall. There is granular cytoplasm, a single nucleus and granules of glycogen and protein and oil globules as reserve food. It was believed that the nucleus is a degenerate one due to occurrence of a vacuole, but now it has been found to be a true nucleus.


Under favourable conditions, i.e., when there is sufficient food, yeast cells reproduce vegetatively by budding. This is the most common method of reproduction in this fungus. A bud or protuberance arises at one end of the cell and gradually enlarges.

The nucleus divides into two by mitosis. One nucleus with some cytoplasm and food flow from the mother cell to the bud. By constriction the bud is separated from the mother cell. By this process a large number of buds are produced which may often remain in the form of short chains (Fig. 196). The idea that the nuclei divide directly by amitosis during the process of budding has been found to be incorrect.

A few of them are called fission yeasts, in which the proto­plast of the mother cell is separated into two parts by the forma­tion of a septum, rather than by constriction as in budding. When food supply is exhausted yeast cells produce spores.

Individual cells enlarge and the nuclei divide once, twice, or thrice, forming 2,4, or 8 nuclei in each cell. Cytoplasm collects round each nucleus and ultimately resistant spores are formed.

The spores are called ascospores and the mother cell (sporangium) is known as ascus. The ascus wall breaks to liberate the asco­spores. Each of them goes on reproducing by budding in suitable medium. This process, described as asexual, is really parthenogenetic (Fig. 197).

Sexual reproduction takes place in some species of yeast by conjugation. Two yeast cells approach each other and touch, where short protuberances are formed.

Dissolution of the wall results in the formation of a short conjugation tube connecting the two cells. The two nuclei move to the tube which broadens considerably and, as a result, the whole thing takes up more or less barrel-shaped appearance. The nuclei fuse in the tube forming zygote (diploid) nucleus.

The zygote nucleus usually divides thrice, of which the first division is reduction division. Cytoplasm collects round each nucleus and usually eight spores are delimited. The spores are the ascospores and the barrel-shaped sporangium is the ascus (Fig. 198). Ascospores come out of the ascus and reproduce by budding is suitable medium.

Alcoholic Fermentation:

Yeast has the property of setting up alcoholic fermentation in sugary solution. We know that alcoholic fermentation is an energy- releasing process brought about by micro-organisms under anaero­bic conditions. Yeast cells secrete an enzyme, zymase, which de­composes sugar into alcohol and carbon dioxide with liberation of energy. CO2 comes out as bubbles forming froth.

It may be represented thus:

For this particular property yeasts are used commercially in breweries for the manufacture of alcoholic beverages like wines, beers, etc. The same principle applies in the preparation of indi­genous liquor, toddy, from sugary exudates. They are also used in bakeries or ‘raising’ of breads.

Yeast cells excite alcoholic fer­mentation in bread paste (dough), and carbon dioxide bubbles, while escaping on application of heat, raise the bread. Yeasts are rich in vitamin B complex. So they have nutritional value as well.

Saprophytic Fungus # 3. Penicillium:

Penicillium is a common saprophytic fungus growing on decayed organic matters like bread, jam, jelly, vegetables and fruits and even on damp shoes and leather. It is known as green or blue mold. The spores -of this fungus are abundantly present everywhere and often cause considerable damage to fruits and vegetables.

Some species are also used in industries. Sir Alexander Flemming isolated the wonder drug, penicillin from Penicillium notatum in 1929. The antibiotic peni­cillin had revolutionised medical science and proved to be a real boon to humanity.

The mycelium is composed of much branched septate hyphae occurring in tangled masses. They ramify extensively on the subs­tratum and many of them penetrate into it to serve as rhizoids. The hyphal cells are multi-nucleate.


This fungus reproduces mainly by asexual method, through the spores called conidia, which are formed in very large number. Sexual method of reproduction has also been reported in some species, though the stages are not very clearly known.


Some stout hyphae come out erect from the mycelium and function as conidiophores. Smaller branches develop from the tip of the conidiophore, which again divide to form a row of closely- packed branches called sterigmata. Un-branched chains of asexual spores—conidia, are cut off from the tip of the sterigmata in basipetal order (Fig. 198A).

The terminal portion of conidiophores with branches and chains of conidia together looks like a broom and is called penicillus—meaning broom. The conidia are globose, ovoid or elliptical with smooth or spiny surface and usually green in colour.

They are uninucleate at the early stage but may become multinucleate in some cases. The conidia are easily dispersed by wind, and germinate on a suitable substratum. A germ tube is first formed which ultimately develops into a new mycelium.


Sexual reproduction, though not clearly known, is oogamous. A hypha comes out erect, enlarges, becomes club-shaped and develops into the ascogonium. The nucleus divides again and again to form 32-64 nuclei dispersed in the cytoplasm of the ascogo­nium. In the meantime another branch comes out of a neighbouring hypha which twines round the ascogonium.

The terminal part of that branch is cut off by a septum, swells and forms the antheridium. It comes in contact with the ascogonium where a pore is formed for movement of the protoplast of the antheridium to the ascogonium. Though gametic union has not been established it may be assumed that the process takes place. By formation of septa the multinucleate ascogonium gives rise to a row of bi-nucleate cells.

Many hyphae with bi-nucleate cells now develop from these cells—which are called ascogeneous hyphae. They become septate, each cell having two nuclei, and the terminal cell develops into an ascus. The two nuclei of the ascus fuse to form the zygote nucleus, which then divides thrice, the first division being reductional, and ultimately produces eight ascospores.

Meanwhile sterile vegetative hyphae send out many branches around the sex organs forming a closed fruit body—the ascocarp. This cover made of hyphal cells is known as cleitothecium, the inner layer of which is nutritive in function. With maturity of the Ascospores the asci dissolve leaving them free and scattered in the cleistothecium. The periderm now decays liberating the ascospores which are easily blown off by wind.

The Hardness Test

Mineralogist Frederich Mohs devised a scale from 1 to 10 to classify minerals by hardness. The harder a mineral is, the more likely it is to be valuable. If you can scratch the mineral with your fingernail, it has a hardness of 2.5 Mohs, which is very soft. If you can scratch it with a penny, its hardness is 3 Mohs, and if it takes a piece of glass to scratch it, the hardness is 5.5 Mohs. Any stone that scratches porcelain instead of leaving a streak has a hardness of about 6.5 Mohs. Diamond is the hardest mineral its hardness is 10 Mohs, and you can scratch one only with another diamond.

Igneous Rocks

Igneous rock is created by volcanic activity, forming from magma and lava as they cool and harden. It is most often black, gray, or white, and often has a baked appearance.

Igneous rock may form crystalline structures as it cools, giving it a granular appearance if no crystals form, the result will be natural glass. Examples of common igneous rock include:

  • Basalt: Formed from low-silica lava, basalt is the most common type of volcanic rock. It has a fine grain structure and is usually black to gray in color.
  • Granite: This igneous rock may range from white to pink to gray, depending on the mix of quartz, feldspar, and other minerals it contains. It is among the most abundant type of rock on the planet.
  • Obsidian: This is formed when high-silica lava cools rapidly, forming volcanic glass. It is usually glossy black in color, hard, and brittle.

Difference between polyp and medusa

Movement of polyp and medusa

Polyp is a sessile life cycle stage of the Cnidaria phylum, while medusa is a mobile life cycle stage of the Cnidaria phylum.

Morphology of polyp and medusa

Polyps have a tubular shape and are fixed at their base. Their mouth is present at the other end of the tube, and is surrounded with tentacles forming the “head”. Mouth and tentacles face the water.

In contrast, medusa have the shape of a contracting muscular bell enabling it to swim. In Hydrozoa species, the mouth is present at the end of a tube hanging down from the bell known as the manubrium. Tentacles, photoreceptors, and gravity-sensing statocytes surround the bell.

The photoreceptors and the statocytes are sense organs present only in medusa and lacking in the polyp.

Reproduction of polyp and medusa

Polyp reproduction can be asexual by budding through the evagination of a circular are of tissue including the endoderm and ectoderm, or sexual by spawning following the release of pheromones. Polyps exist as separate sexes or hermaphrodites. Budding of polyps can produce either polyps or medusa.

Medusa, however, can only reproduce sexually, giving birth to medusa only.

Evolution of polyp and medusa

Polyp are the primitive form of Cnidaria, with medusa being the more evolved form.

Medusa are free swimming, reproduce sexually with cross-fertilization increasing genetic diversity, and present a more complex morphology than the polyp form. While polyp lack the presence of sense organs, medusa have photoreceptors and gravity-sensing statocytes.

Watch the video: Ξεχωρίζω τα πρόσωπα Α - Β τάξη (January 2022).