Question

1-Which of the following organisms possess a closed circulatory system?

Group of answer choices

1-penguin

2-lung fish

3-octopus

4-All of these possess a closed circulatory system

earthworm

Question 2

2-What do Poriferans lack that excludes them from the Eumetazoa?

1-Group of answer choices

2-true tissues

3-a complete digestive tract

4-an open circulatory system

nerves

Answer 1

1. 4.All of these possess closed ciculatory system.

In a closed circulatory system the blood is confined to blood vessels and travels in a closed circuit circle (from heart and back to heart). Here Penguin, lung fish and octopus have a closed circulatory system with heart but in case of earthworm heart is absent but blood circulates exclusively through vessels. They have ventral and dorsal blood vessels to carry blood.

2. 2. True tissue

Poriferans do not have true tissues because they do not create a true gastrula during embryogenesis, and as a result do not produce a true endoderm or ectoderm. But ofcourse they have specialized cells to perform different functions and thus, the poriferans can be said to have tissues; however, these tissues are likely not embryologically homologous like Eumetazoa. This made them groupes under Parazoa.