Difference Between Algae and Bryophytes

Main Difference – Algae vs Bryophytes

Algae and bryophytes are two types of primitive autotrophs found on earth. Both organisms exhibit undifferentiated, thalloid body structure. Algae play a vital role in ecosystems like fresh and marine water, as primary producers and oxygen producers. The most primitive land plants are bryophytes, living in intermediate of aquatic and terrestrial environment. Bryophytes are considered to be evolved from algae. Cell walls of both algae and bryophytes are made up of cellulose. Both algae and bryophytes lack a vascular system. The main difference between algae and bryophytes is the division of the plant body; no division of labour is observed in the plant body of algae whereas the plant body of bryophytes internally divides into photosynthetic and storage zones.

This article explores,

1. What are Algae
      – Definition, Classification, Characteristics
2. What are Bryophytes
      – Definition, Classification, Characteristics
3. What is the difference between Algae and Bryophytes

What are Algae

Algae are the plant-like organisms, which are classified under kingdom Protista. They are mostly unicellular and found in fresh, marine and wastewater habitats. Most of the algae are autotrophs, containing photosynthetic pigments in their cells. Heterotrophic and mixotrophic algae types are found as other nutrition modes. Mixotrophic algae use nutrition modes, autotrophy and heterotrophy. Autotrophic algae serve as the primary producers of aquatic food chains. Around 70% of breathing oxygen is produced by algae.

All cells in the plant body of algae are capable of growing and reproducing. The size of algal body is varied from microalgae to macroalgae. Cyanobacteria are prokaryotic microalgae. They are called blue-green algae as well. Sea-weeds are macroalgae. Algae produce motile spores during asexual reproduction. Sexual reproduction of eukaryotic algae occurs by the union of male and female gametes, which are produced in different individuals. Hence, eukaryotic algae are sexually dimorphic. Fresh water algae in a pond are shown in figure 1.

Figure 1: Fresh water algae

Classification of Algae

Chlorophyta, Rhodophyta and Phaeophyta are the three morphological types of algae. Chlorophyta is the most diverse group of algae. Chlorophyll, beta-carotene and xanthphylls are the pigments found in Chlorophyta. Hence, Chlorophyta is called green algae. Rodophyta are red algae, containing phycoerythrin as the main photosynthetic pigment. Phaeophyta are brown algae, containing chlorophyll c and fucoxanthin as the photosynthetic pigments. Laminaria saccharina, which is a brown sea-weed, is shown in figure 2. It is commonly called as kelp.

Figure 2:  Laminaria saccharina

What are Bryophytes

Bryohytes are a division of non-vascular land plants, which are classified under kingdom of Plantae. They are spore-producing plants in which the gametophyte stage is dominant in the life cycle. Bryophytes are not seed-producing or flowering plants. They are mostly autotrophs. Some bryophytes like liverworts do not contain chlorophyll; hence, they rely on a fungal partner for food. Bryophytes grow in moist shady places, producing phenolic compounds which deter herbivores. Other plants are also  benefited by the water collected by bryophytes. 

Bryophytes are macroscopic plants and their size varies from a milimeter tall to long strands about one meter. Root-like structures called rhizoids allow the plant to anchor on a surface. Rhizoids are not water absorbing units. Water is conducted internally in the plant body which is absorbed by the plant body itself. Asexual reproduction of bryophytes occurs by fragmentation and small aggregations called gemmae. Water carries sperms to the eggs during sexual reproduction. Fertilization of gametes forms the gametophyte with the spore capsules called sporophyte. Sporophyte produces spores, which are dispersed through the wind. The gametophyte of Oedipodium griffithianum  with gammae is shown in figure 3.

Figure 3: Oedipodium griffithianum gametophyte with gammae

Classification of Bryohytes 

Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts) are the three divisions of bryophytes. Liverworts are flattened moss-like leafy plants. The leaves of the liverworts do not contain costa. But marginal cilia are present in liverworts. Mosses consist of one cell thick, simple leaves, which are attached to a stem. They grow in dense green clumps. Mossses contain costa, which is a midrib, running lengthwise through the leaf. Hornworts consist of a horn-like, elongated sporophyte on the gametophyte. Jamesoniella undulifolia, which is a liverwort is shown in figure 4.

Figure 4:  Jamesoniella undulifolia

Difference Between Algae and Bryophytes

Definition

Algae: Algae are plant-like organisms classified under kingdom Protista.

Bryophytes: Bryohytes are a division of non-vascular land plants classified under kingdom Plantae.

Habitat

Algae: Algae grow in aquatic habitats.

Bryophytes: Bryophytes grow in moist, shady places.

Role in Ecosystems

Algae: Algae serve as the primary producers in aquatic food chains while releasing high proportion of breathable oxygen in to the atmosphere.

Bryophytes:  Bryophytes produce important buffer systems for other plants.

Unicellular/Multicellualr

Algae: Both unicellular and multicellualr algae are present.

Bryophytes: All bryophytes are multicellular.

Plant Body

Algae: Algae can be unicellular or multicellular and filamentous, thalloid or leafy.

Bryophytes: Bryophytes are always multicellular thalloid or leafy.

Division of Labour

Algae: Algal plant body exhibits no division of labour.

Bryophytes: Plant body of bryophytes internally divides into photosynthetic and storage zones.

Pores or Stomata

Algae: Pores or stomata are absent in algae.

Bryophytes: Gas exchange occurs through pores or stomata in bryophytes.

Rhizoids

Algae: Rhizods are absent in algae.

Bryophytes: Two types of rhizoids are found: smooth-walled and tuberculated.

Growth and Reproduction

Algae: Each and every cell in the body is capable of growth and reproduction.

Bryophytes: Only apical cells are capable of growth and reproduction.

Asexual Reproduction

Algae: Zoospores, aplanospores and hypnospores are produced during asexual reproduction of algae.

Bryophytes: Asexual reproduction is absent in bryophytes.

Sexual Reproduction

Algae: Sexual reproduction of algae occurs through isogamous, anisogamous or oogamous.

Bryophytes: Sexual reproduction occurs only through oogamous.

Sterile Jacket

Algae: Sterile jacket is not found covering sex organs of algae.

Bryophytes: Sterile jacket is found surrounding sex organs of bryophytes.

Female Sex Organ

Algae: Oogonium is the female sex organ in algae.

Bryophytes: Archaegonium is the female sex organ in bryophytes.

Zygote

Algae: Algal zygote is liberated from the mother plant.

Bryophytes: Zygote in bryophytes remains in the archegonium.

Embryo

Algae: No embryo formation occurs in algae.

Bryophytes: Embryo is formed from the zygote of bryophytes.

Sporophyte

Algae: Algal sporophyte is independent of gametophyte.

Bryophytes: Sporophyte of bryophytes depends on the gametophyte of bryophytes.

Sporophyte Differentiation

Algae: No differentiation of sporophyte into distinct structures is found in algae.

Bryophytes: The sporophyte of bryophytes differentiates into root, seta and capsule.

Mitospores

Algae: Mitospores are present in algae.

Bryophytes: Mitospores are absent in bryophytes.

Alteration of Generation

Algae: Alteration of generation in algae is isomorphic.

Bryophytes: Alteration of generation in bryophytes is heteromorphic.

Conclusion – Algae vs. Bryophytes

Algae and bryophytes are two types of primitive plants, which are classified under kingdom Protista and kingdom Plantae. Both algae and bryophytes grow in moisture habitats. Most algae and bryophytes are autotrophs. The most prominent photosynthetic pigment in bryophyta is chlorophyll, while algae contain several other types of photosynthetic pigments. Both algae and bryophytes posses thallus-like plant body, which lack roots. Bryophytes exhibit the division of labour into photosynthetic and storage structures. Rhiziods are root-like structures found in bryophytes, which allow the anchoring to the surface. The main difference between algae and bryophytes is the organization of the plant body in each group of organisms.

Reference:
1.Vidyasagar, Aparna. “What Are Algae?” LiveScience. Purch, 04 June 2016. Web. 08 May 2017. <http://www.livescience.com/54979-what-are-algae.html>.
2.”What is a bryophyte ?” What is a bryophyte? – bryophyte. N.p., n.d. Web. 08 May 2017. <https://www.anbg.gov.au/bryophyte/what-is-bryophyte.html>.
3. What is a bryophyte? N.p., n.d. Web. 08 May 2017. <http://rbg-web2.rbge.org.uk/bbs/Learning/whatis.htm>.

Image Courtesy:
1.”864600″ (Public Domain) via Pixabay
2. “fish0183” via (CC BY 2.0) via Flickr
3. “Gametophyte of Oedipodium griffithianum with gemmae” By User:Des_Callaghan – Own work (CC BY-SA 4.0) via Commons Wikimedia
4. “Jamesoniella undulifolia” By Des_Callaghan – Own work (CC BY-SA 4.0) via Commons Wikimedia