The largest plants in the ocean are algae.
Algae are a relatively primitive and ancient type of lower organisms. The structure of algae is simple, without differentiation of roots, stems and leaves. They are mostly single cells, colonies or multicellular fronds. For example, chlorella is a single cell, Volvox belongs to a colony, and kelp is a frond. Algae contain photosynthetic pigments such as chlorophyll, can carry out photosynthesis, and are autotrophic organisms.
There are about 30,000 species of algae, mainly distributed in fresh water or sea water. They are divided into fresh water algae and marine algae, including Cyanophyta, Euglenophyta, Pyrrophyta and Chrysophyta Chrysophyta, Xanthophyta, Bacillariophyta, Chlorophyta. , Rhodophyta and phaeophyta.
Various body forms, including single cells,colonies (consisting of many single cells aggregated, cells do not have close physiological connections), multicellular filaments, and fronds; higher species already have simple tissue differentiation.
The size of algae bodies varies considerably. The smallest are only a few microns in size and can only be seen under a microscope; the largest are visible to the naked eye and the largest are over 100 microns. meters long. Excessive reproduction of certain species can cause phenomena such as red tides (ocean) and algae blooms (freshwater).
The growth and reproduction of algae plants
The reproduction of algae plants includes vegetative reproduction, asexual reproduction and sexual reproduction. There are many ways to reproduce vegetative bodies, including special vegetative branches, such asreproductive branches of black hair algae, which develop independently into new individuals after falling to the ground; there are methods of reproduction that rely on rhizoids, such as Pendoceles algae; there are also methods that rely on disc-shaped larvae to get through the summer or winter.
Asexual reproduction relies mainly on zoospores. These generally have 1 to 4 flagella, chloroplasts and ocelli. They do not have cell walls and have the ability to swim freely. no ability to swim, such as cyanobacteria endospores, Rhodophyta tetraspores, Chlorophyta thick-walled spores, etc. Sexual reproduction relies on gametes, which can be isogametic or heterogametic.
In isogamy, gametes of the same shape and size come together and fuse to form a thick-walled zygote, while in heterogamy, gametes ofdifferent sizes, or even different shapes, fuse to form a zygote. Oogamy is a kind of heterogamy. Female cells are larger and generally cannot swim, while male cells are smaller and have two flagella and can swim freely.
Red algae ovulation is particularly special. The egg sac is called a fruit cell and is a bottle-shaped structure. The eggs are at the bottom of the bottle and the bottleneck is the fertilization thread. The sperm is in the sperm sac and cannot swim and floats with the water. It drifts and sticks to the fertilized thread when it encounters it.
The sperm exits the cyst, enters the fruit cell along the fertilization filament and combines with the egg cell to form a zygote, which immediately develops into a diploid sporophyte of the fruit and parasitizes the fruit. female individual. The fruit sporophyte matures to producespores of the fruit, which transform into independent sporophytes. blueAlgae do not reproduce sexually.