Zoology for the Everyday 'Forger

How many of you like animals?



Anywho, I figured I'd make a thread about some of the cool stuff I learn about animals.
It's a good idea because I'll telling someone about the stuff I'm learning, which will help me remember it!

Mmkay.


Starting with tapeworms:



Alright.
Tapeworms are nasty little suckers.
They have 3 parts to their body.
1. The tip (its head), which has suckers on it. Tapeworms also have a series of small hooks on their tips.
2. The neck, which is right below the tip.
3. The bottom half (or so) of the worm, where each little piece of the worm from that point on is basically a mature baby-making station ready to drop its eggs into its host's body!

But what does that matter to you? Well, having a tapeworm inside you isn't pleasant. Here's why:

If you have a tapeworm inside you, the only way it can stay in your body is if it uses the suckers and hooks on its head to grab on firmly to the inside of your intestines! It just hooks right into your intestines!
Once the head is hooked onto the inside of your intestines, it starts sprouting off little square body links beneath it.
All the new body links sprout off from the tip, and push the older parts down. This means that you can't kill a tapeworm unless you kill its head. If you cut a tapeworm right in half, new pieces will keep growing from under its head!

What's really amazing about these worms is how great they are at being parasites.

First of all, they don't have stomachs, intestines, or any other kind of digestive system.
They absorb everything you eat right through their skin!
This means that if you have a 2-yard-long worm inside of you (and they can be over 20 yards long!), every bit of the outside of that 2-yard worm is sucking food right out of your intestines!

They're great at making babies too.
Every single bit of the worm, except the tip, is devoted to reproduction.
Tapeworms are both male and female at the same time, so a tapeworm can reproduce with itself to make more tapeworms, and make your life a living nightmare!

Almost every little square (called a proglottid) you see in the diagram is a baby-making station, complete with a uterus, vagina, ovary, testes, sperm ducts, and a genital pore to release eggs and sperm into its host!
The proglottids at the very end of the worm (the farthest away from the tip) are said to be "pregnant" because they are very, very, very ready to release their baby worms!

But just how many eggs can a single tapeworm make?
It depends on how long the worm is!

There is one type of tapeworm that has about 80,000 eggs per proglottid!
That worm's boring scientific name is Taeniarhynchus saginattus (try saying that!). It's also known as the "beef tapeworm" (that's a lot easier to say!).

One of the tapeworms that makes the most babies is the broad fish tapeworm, which can shed up to 1 million eggs a day.

Fortunately for humans, we'd have to eat badly cooked, infected meat to get a tapeworm inside us.
But in case that happens, there are medicines out there that attack the tapeworm where it hurts most - its head.

So, did ya read the whole thing, was it interesting, should I continue this thread, and should I go back to studying now?

Sure.

However, I get to post my psychology stuff

I'm waiting for facehuggers, zombies and The Thing.

I'm gonna go drink some acid now.

Jellyfish!

Also known as Cnidarians, Medusae, Hydrozoa, etc., jellyfish are some of the coolest animals out there!

They've got three basic layers to them:
1. Their outside: "Epidermis" (fancy name for skin)
2. The middle part: Mesoglea (jelly-like layer. It has some amoeba-like cells in it)
3. Their inside: "Gastrodermis" (fancy name for lining of the gut - the gut itself is called the "Gastrovascular cavity." The name's not too creative, is it?)

Medusae have tentacles dangling from their bodies. These tentacles are not like octopus tentacles. They have no suckers, although some of them have little adhesive pads on them.
The tentacles have stinging cells. The stinging power of each cell depends on the species. Some medusae stings will merely hurt and cause discomfort, while others (like one species native to Australia) will sting strongly enough to kill a human toddler.
Interestingly enough, those Australian jellyfish may be the strongest stingers out there... but they're only about a foot long!



Anywho, the way the tentacles work is pretty cool.
In the species Hydrozoa, you've got little rings of cells that have a sort of hollow tube going through them (ever seen a strand of beads on a string? It's pretty much like that, only the beads are called "cnida" and the string is really a hollow tube). These stinger cells are called nematocysts.

Pic of nematocysts:




Medusae have a really, really, REALLY simple digestive system.

They use their tentacles to trap food. And I don't just mean trap. Some jellyfish actually surround the prey with their tentacles, sting it to death, and shove the prey right into their guts!
The prey might not die from the stinging, but it'll be shoved into the gut anyway, where it will be digested alive!

Jellyfish digest their prey in their gastrovascular cavity (gut) and then throw the remains right out through the same opening. Their "mouth" (entrance to their gut) also acts as an anus.


One question a lot of people ask is, "If Jellyfish don't have eyes or brains, then how do they know where they are, where the food is, and how to get around?"

It's pretty simple, actually.

Picture a jellyfish in water:


Now, picture what it would look like if you threw a net over it.
That's what its nervous system looks like.

Jellyfish pretty much have a "nerve net" in their epidermis (skin), and when one part of the body is touched, the nerve impulses go through the nerve net and all the cells that touch that part of the nerve net will respond.

Jellyfish don't really think; they don't have brains to think with. They just sense pain or pressure in an area of their body, and the cells around that area will respond to it on their own.
If you cause a jellyfish a lot of harm, for example if you throw a large rock at a jellyfish, most of its body will be aware of the threat and its whole body will respond to it.


Let's take a look at the inside of the jellyfish.

Behold, Class Scyphozoa:



Scyphozoa tentacles are a bit different from the Hydrozoan tentacles. (The hydrozoans are the ones that have the looooong tentacles).
Scyphozoa tentacles are smaller and they form around the edge of the jellyfish.
If you'll look at the edges, you'll see that this jellyfish is not a perfect circle. Its edge has little dips in it. Each little dip you see has a sense organ called a "statocyst," which is a fancy word for a "tells me what's up and what's down" organ.
The jellyfish uses those tiny organs to figure out if it's swimming up, sideways, or down. That way, if a current flips it up-side down, it can swim back into an up-right position.

Jellyfish don't have eyes, though some have light-sensitive cells. Basically, they can tell if it's dark or if it's bright.

The four-leaf clover shape on the inside is called a "gastric pouch," which basically means that each part of that shape is a part of its gut.

The four tentacle-like things growing on the inside are just that - tentacles.


Let's talk about JELLYFISH SEX!!



Jellyfish have pretty strange life cycles.

They can live as free-living (swimming) medusae (like the two in the picture above), or they can live as polyps:




Their life cycle basically works like this:

Two medusae (swimming jellyfish), one male and one female, meet and bump uglies. Just like humans, jellyfish make sperm and eggs!
When they bump uglies, they release the sperm and eggs. Those will then mix in the water.

The little zygote that forms will grow into a larva, which will settle down on the ocean floor.

The larva will then grow into a polyp.

The polyps will usually grow together, so it's really common to see groups of polyps:



See how their tentacles look grainy?
That's another way that the stinging cells grow. All the grainy dots are stinging, horribly painful, cells.

Anyway, polyps have a few ways of reproducing:

1. They'll actually grow little sperm-filled or egg-filled buds (depending on their gender) on their stalks. The sperm and eggs will spray out into the water, mix together, and make a new polyp!
2. The polyps can just grow to be really big, and at some point they'll form a special kind of polyp called a gonozooid. Funny name!
These gonozooids are baby-making stations! These baby-making stations will grow little bumps on it, and those bumps will grow to be baby jellyfish that will swim away!


Once those jellyfish grow up, they'll find a jellyfish of the opposite gender. They'll bump uglies, release sperm and eggs, form zygoes, which will grow into larva, which grow into polyps, etc. The whole cycle just repeats itself over and over again.

However, some jellyfish live ONLY as polyps (polyps will have baby polyps) and some jellyfish live ONLY as jellyfish (jellyfish will have baby jellyfish).

How long they live as polyps or jellyfish really depends on the species.


Eye candy:

Nice thread TKO.

Hey, when you do lobsters ans such... make sure to point out their relation with the cockroach...

I think snails are next.

I'm typing these posts up as I learn about animals. My favorite ones make it to the thread.

When we get to lobsters, I promise I'll type up a posts on lobsters whether they're my favorites or not.

Phylum Platyhelminthes and Phylum Nematoda

Planarians are fun (regeneration labs)

Parasites are fun! (one of my favorite lecture of the year for Biology class.

I realize this thread is a PERFECT example of TLDR.

I'm doing this mostly to help me remember what I study. I wasn't expecting anyone to read it!

This is cool.

It is fun and informative, please keep it up.

I love this.

I was nearly a biology major in college myself.

TKO, I say this as your friend and ally.

Put anything on spiders up here, and I will personally demote you until you're knee-high to a toddler zombie.

If there's a section on spiders, I'll focus on one spider, make a short post, and include one or two double-spoilered pictures.

I hate spiders. They scare me!

I have a test tomorrow and I am nowhere near ready.
I got lazy for a couple of days and now I'm suffering the consequences.

So I'm gonna make a post on some parasites to remember them better.

ALL SPOILERED PICTURES ARE PROBABLY A LITTLE GROSS TO LOOK AT. IF YOU DON'T WANT TO SEE WORMS OR SWOLLEN LIMBS, DO NOT CLICK THE SPOILER TAGS.

There are 5 important nematode parasites that infect humans.
First up, the ASCARIS LUMBRICOIDES:

That's a pretty harmless picture compared to the others you can find on the internet. These worms are REALLY freakin' long.

The Ascaris Lumbricoides has infected up to 800 million people wolrdwide.
It starts out in the intestine. Females will make a huge number of eggs, which the host will poop out.
The larva will stay in the eggs for a while, molt their skin once while in the eggs, and hopefully get picked up by another host after they molt.
Once a second host picks them up, they go back to the intestine. They leave the eggs and cut through the host's intestine, and swim straight up into the lungs!
They will molt their skin TWICE while in a person's lungs.
Once they do that, they move up the trachea and into the throat, where the host swallows them!

Once they are swallowed, they reach sexual maturity and start the life cycle again.

Here's a picture of a male worm (You can tell because of the hooked tip):

Don't Google pics of ascaris lumbricoides. When these worms leave the host, they look like spaghetti pouring out of someone's anus.



The second important worm is the Enterobius Vermicularis: The Human Pinworm
It's the most common roundworm parasite in the United States.
Pic:


These guys live in the lower part of the large intestine.
Enterobius Vermicularis females will leave the intestines (at night) and lay eggs around a person's anus.
The eggs make the skin itch like crazy, so the sleeping host will scratch the itch and get some worm eggs on his hand.
While he's asleep, he'll probably touch his mouth, so he'll get infected again.

These worms have a Larva stage. They molt their skin 4 times in the small intestine, and then move to the large intestine.




The third important parasite is the Necator Americanus: The New World Hookworm
It's got lips around its mouth. Their lips aren't really lips... they're more like super-sensitive areas that give them information on what is touching their mouths.


The NEcator americanus lives in the Southern U.S.
They live in the small intestine of humans, and they'll hook to the inside of the intestine and eat host's blood and body fluids.
Females will lay 10,000 eggs per day, and the host will poop out most of them.
Larva infect humans by piercing the skin and entering the bloodstream.




The next important parasite is the Trichinella Spiralis: The Porkworm

Ooh, fun. You can get this from eating badly cooked pork!
Adults live in the mucosa (mucous layer) of the small intestine of humans and pigs. They get into the host's circulatory system, and they stay in the blood until they find a muscle (which happens pretty quickly).
They encyst (settle down) in the skeletal muscle for several years.
While they're in your small intestine, they'll molt their skin 4 times.

Here's a pic of a larva inside a person's muscle:





The last important parasitic worm is pretty cool. It's one dangerous motherfucka, and it gets in some pretty uncomfortable places.
It's called the Wuchereria spp. : The Filarial Worms

They look like threads. They're very thin and very long, and they are currently living in 250 million people in tropical areas.
These worms get into your lymph nodes.
One thing your lymph nodes are responsible for is returning certain body fluids into the bloodstream.
If you block the lymph nodes, they can't return fluid to the blood, but they keep receiving fluid.
These worms, since they're thread-like, have an easy time blocking the lymph nodes.
This is what they can do after years of tissue blocking:

That's called elephantiasis!

Wow. That's positively hideous.

Parasitism!

Students love hearing about things like the "scotch tape test"

CLAMS!!!





These guys are amazing.

Alright, bivalves have 3 basic "brains" (bunches of nerves):
One at the "foot" (A part of its body it can use to move or bury itself), one at its esophagus, and one at its main muscle.

If you look at the pic above carefully, you'll see little eyes all over the clam. Guess what? They're full-blown eyes. They have a lens and cornea.

Aside from eyes, the clams also have a statocyst (one of those "tells me if I'm upside-down" organs) near its "brain" in its foot.


If you look at the middle of the picture, you can see the clam's hinge. If you've picked up shells on the shore before, you know that clam shells have a little bulge near the hinge. This bulge is the oldest part of the clam - it's where the clam first started to grow!
The bulge is called an umbo.

Their gills are pretty freakin' cool.
They don't just take air out of water. Oh, no. They filter food out of the water and transport it all the way to the mouth.
That's right! Clams have a mouth!
The gills will form a mucous string that will carry particles of food into the mouth. The string will carry the food past the mouth and into the esophagus, and then into the stomach.
Things get a bit complicated in the stomach.
The mucous string goes in, and it's turned by cells in the stomach. These cells that turn the mucous 'round 'n 'round are called Cilia.
Anyway, as the mucous turns, it'll wrap itself around a crystalline style, which is a rod-like thing inside the stomach. It'll spin and rub the food against a gastric shield, which is like a rough plate inside the animal's stomach.
The turning and rubbing, combined with the stomach's acid, will take the food off the mucous string and digest it.

Clams have an open circulatory system, which means they have no blood vessels. Blood will flow from the heart to the tissue sinuses (some gaps that have body fluids), nephridia (its excretory system - basically a bunch of tubes in its body that throw the waste out), to the gills, and back to the heart.

Clams don't have sex.
()

They are either male or female. Very few clams are both male and female at the same time. They just release gametes (eggs or sperm) into the water when they're near other clams.
The clams will keep sucking in water through their gills, and the eggs and sperm will make it into the body.
The sperm and eggs will mix, and a baby clam will start to grow!


baby clam, also called "veliger larva" or "glochidium."

Some clams actually take care of their babies until they're almost grown up!

It's a freakin' long test, but this is much better than drilling stuff into my head.
I'm making sense of it, so it's sticking better!




Mmkay.

SNAIL TIME!



Okay. Snails go through a really strange puberty.

While they're babies, they just grow. But when they reach "puberty," their internal organs rotate 180 degrees!

There are several advantages to this:
Most of their sensory organs move closer to the head, so it can sense its food or predators better.
The part of the shell that flips up a bit (the shell piece in the pic up there that isn't touching the skin) lets air and water into the body. If the snail didn't turn 180 degrees, that opening would be in the back of its body, and it would draw in water from the ground it has walked in and covered in goo.
The head can hide faster. If that opening is at the front of the body, the head has more room to hide quickly. Hiding the head is extremely important when a snail is under attack!

Anywho.
They have six small "brains" (the clams have 3). These small "brains" are called ganglia.
They are located at the snail's bottom half of its body (the "foot") and in its shell (the "visceral mass").

They have statocysts ("tells me if I'm upside-down" organs) in their foot.

They have osphridia, which is a funny name for some sensory organs that can detect sediment and chemicals in the water and air they breathe in.

Speaking of breathing... snails don't breathe. They don't have lungs. Their mantle (the skin) does all the breathing.
They have one or two gills, and a rolled-up part of their skin that sucks air into the body (it's right under the part of the shell that isn't firmly attached to the skin (you can see that in the pic above)).

Snails have eyes. They are at the tips of the antennae, or at the base of the antennae too.
Their eyes are pretty simple. Mostly a cornea. They can't really make images.

Snails have sex!

()

The snails in this picture are having sex:



Okay. Snails are monoecious, which means they're male and female at the same time.
When they have sex, they can both swap sperm or they can transfer sperm from one to another.
(In other words, they can both be "male" and give each other sperm, or one can be "male" and transfer sperm while the other is "female" and receives the sperm).

That's it on snails!

How can you tell whether you have such parasites, before your limbs swell up or you get ulcers or whatever?

OCTOPUS TIME!!




I love that picture.
I have no idea who took it. But I thank Google for it. It's a great picture.

Remember how clams and snails have a "foot"?
So does an octopus!
Only an octopus' foot is divided into tentacles.
Believe it or not, the octopus is very closely related to the snail and clam!

The octopus's closest relatives are the squid (has a small, internal "shell" called a pen), nautilus, and cuttlefish.
The Nautilus has a shell:

And its eyes don't have a lens on them, so they're exposed to the ocean water.


The octopus doesn't have a shell at all, but it does have lenses over its eyes. Their eyes have a blind spot. They focus by moving the lens back and forth.
Their statocyst ("tells me if I'm upside-down" organ) is in some cartilage near the brain.
The octopus has a large brain formed by a fusion of ganglia. They don't just have scattered "brains." Oh, no. The octopus is smart, it can solve mazes, and it can recognize human faces and tell them apart!

Large areas of the octopus's brain are devoted to muscle contraction, sensory perception, memory, and decision making.

The octopus moves by using its tentacles to crawl, and also by jet propulsion (it shoots water).

An octopus has special suckers on its tentacles that it uses to trap food. All cephalopods (octopus, nautilus, cuttlefish, squid) have powerful jaws. They hunt invertebrates, snails, fish, and crustaceans at night. They use their muscles to shove food into their body.

The octopus has a closed circulatory system, which means it has blood vessels and a heart. Its heart is not simple - it has two auricles and one ventricle!

Their gills take in massive amounts of water every day. Blood vessels run through the gills and take oxygen to the entire body.


Octopus sex is... awkward?
The females make large, yolky eggs that they keep inside their bodies.
The males make spermatophores, which are sperm packets.
The male octopus will put a spermatophore on his tentacle, and then shove his tentacle into the female's body to leave the spermatophore inside her.
Of course, the female can refuse to have some octopus's tentacle shoved into her, and if she wants to, she'll decline him by squirting ink in his face and swimming away.

In case they do make babies, though, here's what you get:



A mother octopus will only care for the eggs, but she'll leave the babies once they hatch. Little fellas like this guy up here grow up alone.

You'll feel sick. Each parasite has different symptoms.
Also, it takes years for limbs to bulge like that. Little bulges are not too much of a problem to fix.

Are bigger bulges more difficult/impossible to fix?

I mean, how can someone just let their leg swell up like that over the years?

Big bulges are pretty much impossible to fix.
Lack of hospitals that can operate on filarial worms usually means people get that sick.
Remember, wucheira spp. lives mostly in tropical countries, so that means it's mostly in the third world.

This is a great thread TKO. Keep up the good work.

Zoology and microbiology are my two favorite subjects to teach

I know how they used to get rid of tapeworms!
You would not eat for a couple days. Then in the doctors office you lie on your side and the doctor places a bowl of warm milk near your mouth.
The worm of course crawls out.
But I'm doubting it until I see it on MythBusters.

I've heard of eating nothing for 3 days and then holding bread up to your anus.



The thing that works best is medication. It kills the tapeworm at the head, which is where it grows.