Characteristics of Invertebrates

• Feeding mechanisms.• Excretion and Osmoregulation.• Circulation and Gas Exchange.• Nervous System.

Feeding mechanisms.(Protozoa and Metazoa)

• Heterotrophic: ingest organic material.

Feeding mechanisms.(Protozoa and Metazoa)

• Heterotrophic: ingest organic material.

I. Intracellular digestion-within a

cell: Endocytosis (phagocytosis

and pinocytosis)

Feeding mechanisms.(Protozoa and Metazoa)

• Heterotrophic: ingest organic material.

I. Intracellular digestion-within a

cell: Endocytosis (phagocytosis

and pinocytosis)

II. Extracorporeal digestion-outside

the body.

Feeding mechanisms.(Protozoa and Metazoa)

• Heterotrophic: ingest organic material.

I. Intracellular digestion-within a

cell: Endocytosis (phagocytosis

and pinocytosis)

II. Extracorporeal digestion-outside

the body.

III. Extracellular digestion-in a gut.

Protista Phylum Ciliophora

Phagocytosis Fig. 3.12

Pinocytosis Fig. 3.12

Phylum Mollusca: Class Bivalvia

Phylum Mollusca: Class Bivalvia

Suspension Feeding

Phylum Echinodermata, Class Echinoidea

Tube Feet Suspension Feeding

Phylum Platyhelminthes, Class Turbellaria

Carnivore

Phylum Annelida Class Polychaeta

Phylum Annelida Class Polychaeta

Deposit Feeding

Excretion and Osmoregulation.

Excretion and Osmoregulation.

• Excretion is the elimination from the body of metabolic waste.

Excretion and Osmoregulation.

• Excretion is the elimination from the body of metabolic waste.

• Osmoregulation is the regulation of water and ion balance within the body fluids.

Excretion and Osmoregulation.

• Excretion is the elimination from the body of metabolic waste.

• Osmoregulation is the regulation of water and ion balance within the body fluids.

• Both vary depending on environment of invertebrates.

Nitrogenous Wastes and Water Conservation (Figure 3.21 A)

H2O H2O

Salt

Salt

Marine (isotonic environment): Organism is isotonic and waste is released as ammonia.

Fresh water (hypotonic environment): Organism is hypertonic and waste is released as ammonia.

Nitrogenous Wastes and Water Conservation (Figure 3.21 B)

H2O

Salt

Nitrogenous Wastes and Water Conservation (Figure 3.21 C)

H2O

Salt (in solution)

Terrestrial (“dry environment): Organisms is hypotonic and waste is released as uric acid.

Excretory and Osmoregulatory Structures

Related to surface-to-volume ratio, and animals bauplan.

1. Contractile vacuoles and water expulsion

vesicles (WEV).

Excretory and Osmoregulatory Structures

Related to surface-to-volume ratio, and animals bauplan.

1. Contractile vacuoles and water expulsion

vesicles (WEV).

2. Nephridia (Protonephridia and

Metanephridia).

Circulation and Gas Exchange

• The transport of materials from one place to another depends on the movement and diffusion of substances in body fluids.

Utilize water from the environment as a circulatory fluid.

Fig. 3.24

Pseudocelomates use fluids in the body cavity for circulation.

Fig. 3.24

Pseudocoelom

Fig. 3.24

Closed circulatory system (annelids)

Open circulatory system (arthropods)

Gas Exchange and Transport

Outside Inside

Fig. 3.26

External modifications to increase surface area

to volume ratio

Nervous System and Sense Organs.

SEM of cross sections of a Nematomorph

Ventral Nerve Cord

The Big Picture

The size and bauplan of invertebrates determines the type of excretory, osmoregulatory, circulatory, gas exchange, and nervous system.

The diversity comes from the constraints placed on the particulate invertebrate group due to its bauplan.