Question

Compare and contrast the anatomy and reproductive strategies of annelida and arthropoda . include body plan, digestive system, neuroanatomy , excretorey and reproductive system

Answer 1

Annelids and arthropods:

Both Annelida and Arthropoda are phyla in the Linnaean classification system. But Arthropods and annelids are different types of organisms. The Annelida phylum includes most worms, while the diverse Arthropoda phylum counts arachnids, lobsters and insects among its members.

Anatomical difference:

Members of the Annelida and Arthropoda phyla differ in their body formations. Annelid species typically have tubelike bodies consisting of numerous segments, known as somites, covered in stiff hairlike structures called setae that help the annelid move forward. Leeches have somites but not setae; instead, they have suckers on both ends of their flatter bodies. On the other hand, arthropods have more complex segmented bodies covered in an exoskeleton that protects their organs and muscles. Most arthropods also have visible distinctions between their heads, bodies and legs; this is not the case for annelids.

Reproduction strategies:

Reproduction among arthropods usually involves a male and a female of the species mating in order to fertilize eggs in the female, who then lays the eggs. Some arthropods fertilize their eggs externally. Most species are dioecious, meaning they have two distinct sexes. The polychaete class of annelids is also dioecious, but most members of the other two classes are not. For example, a single earthworm will produce both eggs and sperm. Two worms rub against each other to exchange sperm and to fertilize one another's eggs. The polychaete class can also reproduce through epitoky, Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm (the atoke) is modified or transformed into a sexually mature worm (the epitoke) and In some of these cases, part of the worm separates from the rest of the body and leaves the burrow to reproduce. The remainder of the worm stays behind in the burrow.

Digestive system:

In Annelids,Digestive tract is complete, straight and extends through entire body. The gut has both circular and longitudinal muscles. Few annelids are sanguivorous. Digestive gland are developed for the first time in Annelida.

In Arthropods,Digesive tract is complete

It has divided into three parts:

(1) Stomodaeum (Anterior)

(2) Mesenteron (Middle)

(3) Proctodaeum (Posterior)

Straited muscles are found in digestive tract.

Mouth parts adapated for-

(1) Biting and chewing: Biting and chewing type:Grasshopper, Cockroach, Termites, Caterpillers.

(2) Piercing- Sucking type - Mosquitose, Bugs, Fleas.

(3) Chewing- lapsing type – Bee

(4) Sponging type -Housefly, fruitfly.

(5) Siphoning type - Butterflies, moths

Excretory system:

In Annelids,Excretory organ is Nephridia. Coiled tubules also helps in osmoregulation.

Excretory matter

(1) Ammonia in aquatic form

(2) Urea in land form

In arthropods,Excretory organs are –

(1) Antennary or green glands-or maxillary gland (e.g. Crustaceans) opening directly to the exterior.

(2) Coxal gland (e.g. Arachnids)

(3) Malphigian tubules (e.g. Insects) opening into the gut.

Excretory matter is ammonia in aquatic animal and uric acid in land animals

In annelids,Nervous system consist of –

A circumenteric nerve ring, Double, midventral nerve cord with ganglia. Sence organ chemoreceptor, photoreceptor & tentacle, palp, eyes may be present.

In arthropods,Nervous system comprises of a circumenteric ring and a double, solid midventral nerve cord bearing a pair of ganglia per segment or less (Ganglia)