Are octopuses ectothermic or endothermic?
As ectotherms, cephalopods are required to sustain metabolic performance and thus body functions at their respective habitat temperature.
How do mollusks grow and develop?
Many mollusks develop into free-swimming larvae; these larvae are either feeding (planktotrophic) or nonfeeding (lecithotrophic). In these generally planktotrophic larvae, the girdle of ciliated cells widens to form a velum that entraps food and also propels the microscopic mollusk through the water.
What is the average lifespan of a mollusk?
Mean observed lifespan = 22.47 for the entire database.
Do all mollusks have brains?
Molluscs, with the exception of the most highly developed cephalopods, have no brain in the strict sense of the word. Instead, the cell bodies (pericarya) of nerve cells are concentrated in nerve knots (ganglia) in important parts of the body. Mollusc nerve cells have no myelin sheath.
Do all mollusks have eyes?
Molluscs have eyes of all levels of complexity, from the pit eyes of many gastropods, to the pinhole eyes of the Nautilus, to the lensed eyes of the other cephalopods. Compound eyes are present in some bivalves, and reflective ‘mirrors’ have been innovated by other lineages such as scallops.
Are mollusks blind?
Only they have got the eyes at the end of the long tentacles. Eye stalks can also be found among some marine gastropods, for example conches (Strombidae). But they mainly enable the snail to look from under its shell without having to expose its head, not noticeably increasing its field of vision.
What animal has the most eyes?
Mantis shrimp eyes are compound like a dragonfly, but they only have 10,000 ommatidia per eye. Still, mantis shrimp have the most complex eyes of any animal known on Earth — they have 12 colour receptors (compared to humans only having three), as well as ultraviolet, infrared and polarized light vision.
What animals are considered mollusks?
The molluscs include many familiar animals, including clams, snails, slugs, and squid, as well as some less familiar animals, like tusk shells and chitons (Fig. 3.51 A). Molluscs are found in nearly all freshwater and marine environments, and some are found also on land.
What are 3 types of mollusks?
The three major groups of mollusks are gastropods, bivalves, and cephalopods (SEF ul o pods). The largest group is the gastropods. These are mollusks like snails and slugs that have just one shell or no shell at all.
Do mollusks travel alone?
Do mollusks travel alone? Mollusks, from land snails and slugs to oysters and mussels in the sea, have a few things in common. It also helps them travel, but not very fast. When the mollusks are young tiny things floating in the ocean, that’s when they really start to move.
How do you identify mollusks easily?
Characteristics of Mollusks Without a spine, it’s easy to see why mollusks have soft bodies. Their bodies are made up of three main parts, including a muscular foot, a visceral mass, and a mantle. The foot is an appendage that some mollusks use for movement and others use for burrowing.
What color is a gastropods blood?
As in other molluscs, the circulatory system of gastropods is open, with the fluid, or haemolymph, flowing through sinuses and bathing the tissues directly. The haemolymph typically contains haemocyanin, and is blue in colour.
How many hearts does a snail have?
Snails usually have two heart chambers, one atrium and one ventricle. Few groups have two atriums, making the heart a three-chambered one. There is a valve between atrium and ventricle to prevent the blood from flowing back. Snails’ circulation basically is open.