Octopus
Octopus is a cephalopod of the class of mollusks. It has eight arms that can reach a length of up to 3 meters. Octopus is perfectly
adapted to the life of the hunter, but to the prey as well, because it has a secret weapon. The body folds hide an ink bag, which when
released is supposed to confuse your enemies. Her baggy body hides an extremely well-developed brain and nervous system, which
makes the octopus surprisingly intelligent sea animal.
It lives on rocky shores mostly in holes or crevices of rocks in shallow water. Sometimes it transfers stones with its arms and builds a sort
of fort on the seabed. Octopus moves floating or crawling along the seabed on the top of tentacles and when escaping it moves
backwards. Preferably it always hides in the same shelter. Shelter is recognized by neat piles of larger and smaller stones in front of the
hole. Males are distinguished from females by slightly larger tentacles.
Octopus is sensitive to cold, and many of them die in winter time in shallow areas along the coast due to low temperature. Octopus
dipped in fresh water dies in a matter of seconds.
During the daytime octopus spends most of the time in its hideout observing environment. Its large eyes with lids adapted to dim light
under the water can detect motion and identify the structure.
It goes out of its hiding place only when it gets dark searching for food. Her favorite food is clams, crabs and shellfish. Although the
octopus is an excellent swimmer, it usually hunts its prey using cunning. It can change the color of the body and thus be adapted to the
environment. It will lye masked on the seabed and rush itself into careless trespasser stunning it with nerve poison. Its long, powerful
arms are stretchable and are equipped with two rows of suction caps that an octopus uses to firmly hold the slippery prey.
If the victim is some sort of hard-shell mollusk, octopus will break the shell with its "parrot beak" jaws. When it wants to catch some much
more dangerous prey, such as lobster, it uses the cunning method. First it releases a shroud of darkness to reduce visibility, moving
cautiously through the cloud grabbing the lobster from behind so it would not be able to use its pincers for defense.
The octopus' enemies are conger eels, dolphins and sharks, to which it is often food. If possible, the octopus will run as fast as possible
with its "jet drive" spitting blackness. In addition, octopus has the ability to pull through very small openings through which the enemy
cannot follow and remain confused in front of her shelter.
Its ability to paint itself to the environment, octopus prevents to be noticed. It can allocate the color pigments in its skin as desired,
condensing them in some areas and diluting in other to get more consistent with the environment.
The most effective method of defense is the same one they used in hunting. If someone follows, it will release a large cloud of water in the
blackness. At the same time and releases a substance that diminishes opponent's sense of smell so that he will no longer be able to find
it.
It also has a 'fang' located in the center bottom of the octopus, where its arms begin to spread. Fishermen take care to remove the tooth
when they catch an octopus to not to get hurt.
Octopus that mate seem to be holding hands, but in reality the male is using a special branch, called hectocotyli, injecting spermaphore
(seminal bags) into the mantle to females to fertilize the eggs. A week later the female lays eggs in a cluster of encapsulating them with
jellylike mass fixing them to the wall. During the four to six weeks, as needed, the eggs hatch into larvae. In that time octopus takes care
of the eggs, often touching them, cleaning them and bringing them fresh water. This concern while spawning may be lethal to an octopus
because at that time it eats nothing can completely lose its strength and die. The eggs will hatche into larvae of only 3 mm long that look
like miniature octopus. They float together with plankton for some time but later they lower themselves to the seabed, where they rapidly
grow.
Hobotnica
Hobotnica je mekušac iz razreda glavonožaca. Ima 8 krakova s kojima može dostići duljinu i do 3 metra. Hobotnica je odlično
prilagođena životu lovca, ali i plijena, jer ima tajno oružje. U tjelesnim naborima krije vrećicu s crnilom koje ispušta kad želi zbuniti svoje
neprijatelje. Njezino vrećasto tijelo krije iznimno dobro razvijen mozak i živčani sustav, zbog čega je hobotnica iznenađujuće inteligentna
morska životinja.
Živi na stjenovitim obalama i većinu vremena provodi u rupama ili raspuklinama stijena u plitkoj vodi. Katkad krakovima prenosi kamenje i
gradi neku vrstu "utvrde" na morskom dnu. Hobotnica se kreće plivajući ili pužući po dnu na vrhovima krakova, a pri bijegu se kreće
unatrag. Po mogućnosti se povlači uvijek u isto sklonište. Sklonište se prepoznaje po uredno naslaganom većem i manjem kamenju
ispred rupe. Mužjaka se od ženke razlikuje po nešto većim prianjalkama.
Hobotnica je osjetljiva na hladnoću i zbog toga ih mnogo ugiba zimi u plitkim predjelima uz obalu zbog niskih temperatura mora.
Hobotnica zamočena u slatku vodu ugiba za nekoliko sekundi.
Danju hobotnica većinu vremena provodi u svom skrovištu i pritom promatra okolinu. Njezine velike oči s kapcima prilagođene su
prigušenom svjetlu pod vodom pa mogu razaznati gibanja i prepoznati strukture.
Izlazi iz svojeg skrovišta tek kad se smrači te odlazi u potragu za hranom. Njezina omiljena hrana su rakovi, rakovice i školjkaši. Iako je
hobotnica odličan plivač, najčešće svoj plijen lovi primjenjujući lukavstvo. Može mijenjati boju tijela i tako se prilagoditi okolini. Ležeći
maskirana na morskom dnu promatrat će okolinu i jurnuti na neopreznog "prolaznika" te ga omamiti svojim nervnim otrovom. Njezini dugi i
snažni krakovi rastezljivi su i opremljeni s dva reda prianjalki, kojima hobotnica može čvrsto držati i sklizak plijen.
Ako je njezina žrtva neki mekušac s tvrdom ljušturom, hobotnica će razbiti ljušturu svojim "papagajskim kljunom" tj. čeljustima sličnim
kljunu. Kad želi uloviti neki mnogo opasniji plijen, poput hlapa, služi se lukavijom metodom. Najprije u vodu ispusti oblak crnila i tako
smanji vidljivost, a zatom se kroz taj oblak oprezno približi hlapu i zgrabi ga sa stražnje strane kako ovaj ne bi mogao upotrijebiti svoja
kliješta za obranu.
U neprijatelje hobotnice ubrajaju se ugori, dupini i morski psi, kojima je ona česta hrana. Ako je moguće, hobotnica će im pobjeći
najvećom mogućom brzinom pomoću svog "mlaznog pogona" te izbaciti crnilo. Hobotnica osim toga ima sposobnost da se provuče kroz
vrlo male otvore kroz koje je neprijatelji ne mogu slijediti pa ostaju zbunjeni ispred njenog skloništa.
Svojom sposobnošću da se bojom u potpunosti prilagodi okolini hobotnica, već unaprijed sprečava da je netko otkrije. Ona pigmente boje
u svojoj koži može rasporediti po želji, može ih na nekim mjestima zgusnuti, na nekima razrijediti te oblikovati pruge i uzorke koji su u
skladu s okolinom.
Najučinkovitija obrambena metoda jest ona ista koju koristi i u lovu. Ako je netko slijedi, ispustit će u vodu velik oblak crnila. Istodobno
ispušta i tvar koja umrtvljuje osjetilo mirisa protivnika tako da je on više neće biti u stanju pronaći.
Mora se spomenuti i 'otrovni zub' koji se nalazi u središtu gdje izrastaju krakovi, ispod hobotnice. Ribolovci paze da taj zub uklone kada
ulove hobotnicu da ne nastradaju.
Hobotnice koje se pare izgledaju kao da se drže za ruke. No u stvarnosti mužjak pomoću posebnog kraka, koji se naziva hektokotilus,
uštrcava spermafore (sjemene vrećice) u otvor plašta ženke kako bi oplodio jajašca. Tjedan dana kasnije ženka polaže jajašca u obliku
grozdastih nakupina, oblaže ih želetinoznom masom i pričvršćuje za stijenu. Tijekom četiri do šest tjedana, koliko je potrebno da se iz jaja
izlegu larve, čuva jajašca, često ih dodiruje i čisti te im dovodi svježu vodu. Ta briga za mrijest može je stajati i života jer za to vrijeme
ništa ne jede pa može u potpunosti izgubiti snagu i uginuti. Iz jaja će se izleći ličinke duge samo 3 mm,koje izgledaju kao minijaturne
hobotnice. Zajedno s planktonom plutaju neko vrijeme u vodi da bi se kasnije spustile na morsko dno, gdje brzo rastu.